6.1 Introduction
Self-defence is one of the longest established authorities for using force, as illustrated by the medieval maxim “all laws, written and unwritten, permit force to be repelled by force” (Vim vi repellere omnes leges omniaque iura permittant).1 Self-defence also plays an important role for military forces for whom the risk of being attacked is an occupational hazard. As explained in Section 3.2, roe commonly include a reference to the ‘inherent right of self-defence’ which may never be limited by roe. The phrase is included for all types of operations, including those involving participation in armed conflict. However, despite the general agreement that military forces participating in an armed conflict have a right to defend themselves, the legal basis for this right is unclear. One commentator goes so far as arguing that “there is significant ambiguity – if not outright legal lacunae – as to the origin and limits of this right”.2 What is clear, however, is that military forces have a right not to be arbitrarily deprived of their lives, and as a result, retain a right to use defensive force in exceptional circumstances.3
The use of force by military forces will need to comply with applicable law in order not to be arbitrary. Because military forces generally are not tasked with law enforcement, the use of force must either comply with loac or amount to self-defence.4 As explained in Chapter 5, loac regulates the use of force in both offence and defence.5 This begs the question whether the legal concept of self-defence has any role to play at all in the context of armed conflicts, and if so, how it applies. In addition, it is necessary determine which form of self-defence applies.
There appears to be a military trend, at least in recent years, to refer to self-defence in a wide variety of situations.6 For instance, a nato attack on Pakistani forces near the Afghan border in 2011, killing 28 soldiers, was alleged to have been an act of self-defence.7 Similarly, the 2015 U.S. airstrike on the Doctors Without Borders Hospital in Kabul, killing 22 civilians, was called in by U.S. Special Forces in self-defence of U.S. and Afghan forces.8 When acting in self-defence in military operations, will military forces be applying jus ad bellum self-defence or personal self-defence as set out in national criminal law? Do the references commonly found in military doctrine to a universal right of self-defence suggest that there is a right of self-defence for individuals set out in international law? As will be further explained in Chapter 8, it appears that references to self-defence in military doctrine and practice focus on the ability to use defensive force, rather than its legal basis. Self-defence is cited in situations where it is difficult to see how a legal concept of self-defence could apply and where the defensive force would be permitted by loac. Such references should in other words not necessarily be considered determinative of the legal authority for the use of force.
Traditionally, self-defence is viewed as applying to States and persons, and roe may regulate the use of force in both cases. According to the icj, the right of States to act in self-defence is a “fundamental right of every State”.9 The relevance of State self-defence to an ongoing armed conflict depends on the approach taken to the relationship between the jus in bello and jus ad bellum. As explained in Chapter 4, the use of force during an ongoing armed conflict must comply with the jus in bello, unless it is an exercise of self-defence. State self-defence does not authorise force against an adversary which is not permitted by loac, or phrased differently, the jus ad bellum cannot be relied upon to as a defence to a violation of the jus in bello. As Hessbruegge explains, “Article 51 can only justify the infringement of another state’s territorial integrity or sovereignty, but it has nothing to say about whether the killing itself is justified or not”.10 As a result, the reference to self-defence in roe for armed conflict operations must be to a personal right of self-defence.
State self-defence nonetheless continues to be relevant for the understanding of ‘use of force’ categories in armed conflict operations. First, as will be further explained, it appears that the reference to ‘inherent right of self-defence’ in roe originates from U.S. Peacetime roe (proe), where it was a reference to State self-defence.11 State self-defence will therefore have influenced the understanding of the roe reference among U.S. forces who in turn will have influenced other nato States. Second, the legal self-defence concepts are closely connected and sometimes confused, in particular with regard to the use of force in self-defence by military forces.12 For instance, the criteria set out in the famous Caroline incident on State self-defence13 are sometimes used to describe all types of self-defence, as is done in the MC 362/1 on nato Rules of Engagement.14 Finally, not all agree with this exclusion of ad bellum self-defence in the context of armed conflicts,15 and may argue that jus ad bellum is relevant amongst others for military self-defence concepts such as ‘unit self-defence’, further discussed in Section 8.3. As a result, it is useful to begin with an overview of the concept of State self-defence in its various forms (Section 6.2).16
The concept of personal17 self-defence has existed for thousands of years.18 It recognises the right of individual persons to use force to defend themselves and, to some extent, others. The issue in the current context is the extent to which military forces have a right to use force in personal self-defence during armed conflict. Furthermore, is it the same self-defence rule that applies to citizens during peacetime or is it a different form of self-defence? According to Gary Corn, “few issues generate greater emotional debate, both within and outside the armed forces, than the question of whether, and to what degree, servicemembers may use lethal force in the exercise of self-defense”.19
The discussion on personal self-defence (Section 6.3) is divided into two parts. First, it is explored whether the references to a universal right of self-defence or inherent right recognised in international law entails that there are any international forms of personal self-defence (Section 6.3.1). Second, personal self-defence is considered from the perspective of domestic legislation, both in general and as found in a selection of nato States. Because the focus of this part of the book is on the applicable legal bases for the use of force by military forces during armed conflict, non-legal concepts of self-defence will be dealt with in Part iii (Section 8.3), where the relationships between the legal concepts and the operational ‘use of force’ concepts are examined.
As explained in Section 3.2, self-defence plays a central role in the analysis and understanding of nato roe ‘use of force’ categories in several ways. Because nato States have different approaches to self-defence, the meaning and interpretation of self-defence is nationally defined, and the use of force in self-defence is not affected by nato roe.20 While this means that self-defence is not regulated by nato roe, it also means that self-defence is a particularly important ‘use of force’ category because it is the only authority for using force that may not be retained through roe. Furthermore, in order to prevent nato roe from regulating the use of force in self-defence, the nato concepts of ‘hostile act’ and ‘hostile intent’ are defined as regulating the use of force in response to threats not giving rise to a right of self-defence.21 Self-defence is therefore indirectly defining the potential scope of application for these roe. Finally, understanding self-defence is also important for military forces because the use of force in self-defence does not amount to direct participation in hostilities,22 even if it may in practice be difficult to distinguish one from the other.
[t]he absolutely indispensable premise for the admission of a self-contained concept of self-defence, with its intrinsic meaning, into a particular system of law is that the system must have contemplated as a general rule the general prohibition of the use of force by private subjects and hence admits the use of force only in cases where it would have purely and strictly defensive objectives, in other words, in cases where the use of force would take the form of resistance to a violent attack by another.25
Any concept of self-defence should therefore be interpreted in light of the corresponding prohibition on the use of force. Whereas for States, the prohibition is that on the threat or use force against another State, with respect to personal self-defence, the corresponding rules are national criminal law rules on crimes of violence, including murder.26 In the exceptional circumstances when there is a threat or use of unlawful force and the entity authorised to deal with such situations is unable to do so, a right of self-defence arises.27 The entity forced into taking defensive actions should not be held legally responsible for violating the applicable prohibition on the use of force. Self-defence may therefore be viewed as “a ‘privilege’ or ‘liberty’ that justifies conduct otherwise illegal”.28
The differences between the various concepts of self-defence lie in the details: What may be protected? How may it be protected? And from what? Phrased another way, the differences lie in “the constituent requirements of the obligation, i.e. those elements which have to exist for the issue of wrongfulness to arise in the first place and which are in principle specified by the obligation itself”.29 Resultantly, as will be shown below, while the idea of permitting the use of force in response to unlawful force is the same for the differing concepts of self-defence, the entity to which the prohibition on the use of force and corresponding exception of self-defence apply differs, as does the application of the requirements of necessity and proportionality.
In addition to the legal questions surrounding self-defence, there are several interesting ethical and philosophical questions bearing on self-defence, such as the rationale for permitting the sacrifice of one life to preserve another, or for a State to wage a war against another.30 These are not, however, directly relevant to the question at hand and therefore will not be dealt with.
6.2 State Self-Defence
6.2.1 Treaty Law
As explained above, self-defence is an international legal concept providing an exception from the prohibition on the use of force when faced with an unlawful armed attack. In order to understand the development of self-defence, it is therefore necessary to examine the associated regulation of the use of force. The first multinational prohibition on the use of inter-State force was the the 1928 General Treaty for Renunciation of War as an Instrument of National Policy, also known as the Kellogg-Briand Pact or Pact of Paris.31 Previous attempts to regulate the use of force had sought to merely limit rather than prohibit the use of force altogether. The most noteworthy in this regard was the 1919 League of Nations Covenant, which imposed express obligations to employ pacific means of settling disputes and not to resort to war before exhausting such means. 32 Some instruments adopted in the inter-war period went so far as to prohibit the use of force except when used in self-defence.33 However, the Kellogg-Briand Pact was unique in that a record number of States ratified the treaty.34 According to Brierly, the Pact was “the culmination of a strong movement in the early days of the League to outlaw any recourse to force otherwise than in self-defence”.35
Article I stated that “The High Contracting Parties solemnly declare in the names of their respective peoples that they condemn recourse to war for the solution of international controversies, and renounce it as an instrument of national policy in their relations with one another”.36 The Pact did not expressly deal with self-defence as an exception to Article I because it was considered unnecessary; the right of self-defence was viewed as “inherent in every sovereign State and it is implicit in every treaty”.37 However, the Preamble emphasised that “any signatory Power which shall hereafter seek to promote its national interests by resort to war should be denied the benefits furnished by this Treaty”.38 As a result, the prohibition on the use of force did not apply to States that responded to an initial unlawful attack, an exception that resembles a right of self-defence. However, as Dinstein points out, this implicit reference to self-defence did not set out any requirements for the use of force in self-defence, and no competent body was established that could assess the legality of the use of force.39
The right of States to act in self-defence was confirmed in the 1945 UN Charter.40 A clear expression of self-defence was made necessary by the inclusion of a stricter limitation on the use of force. Unlike the League of Nations Covenant, which only ‘condemned’ the use of force, Article 2(4) the UN Charter sets out a clear prohibition on both the threat and use of force: “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations”.41 If a situation is considered to amount to a threat to international peace and security, the UN Security Council has in Chapter vii of the Charter been given the power decide what measures shall be taken “to maintain or restore international peace and security”,42 including authorising the use of force.43 However, these collective measures may not be sufficient, or more importantly, may be too late, with the result that States continue to be dependent on the possibility for using force in self-defence. This is reflected in Article 51, where it is made clear that “Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security”.44 The application of Article 51 will be discussed further in Section 6.2.3.
6.2.2 Custom and Practice
As explained above, one of the reasons that self-defence had not been included in previous treaties was that it was considered unnecessary. It almost did not make it into the UN Charter either. According to Gill, “[i]t was only included relatively late in the travaux leading to the Charter’s adoption at the behest of Latin American States seeking a guarantee of the legality of regional collective self-defence arrangements, such as the Act of Chapaltupec”.45 Rather than merely setting out a right of self-defence, Article 51 specifies that the UN Charter does not impair an existing right of self-defence. While it has been contended that the last-minute inclusion of Article 51 limits its impact on international law,46 this assertion seem untenable in light of the repeated reliance on the Article by the International Court of Justice.
The historic recognition of self-defence is reflected in the reference in Article 51 to the pre-existing or ‘inherent’ right of self-defence, or ‘droit naturel’ in the French version.47 It was for instance much debated by classic writers on international law who discussed the limits on States’ prerogative to use force. For instance, according to Grotius (1583–1645), “[t]his right of self-defence, it should be observed, has its origin directly, and chiefly, in the fact that nature commits to each his own protection”.48
The transformation of the naturalist ideas of self-preservation and just war theory into a more specific legal concept of self-defence is commonly accredited to the ‘Caroline’ incident of 1837 and the subsequent debate between the U.S. and Great Britain.49 The Caroline was a U.S. vessel being used by U.S. nationals to support rebels in Canada during the Mackenzie Rebellion by transporting persons and equipment. Canada was at the time a British colony, and British forces attacked and destroyed the vessel while it was on the U.S. side of the Niagara River. The vessel was attacked at night, while moored to the shore of Navy Island and with people sleeping on board. It was then drawn into the current, set on fire, and cast adrift over Niagara Falls. Two U.S. nationals died. Alexander McLeod was later arrested in New York by U.S. authorities for his participation in the attack.50 The incident led to an exchange of letters between U.S. Secretary of State Webster, the representative of the British Crown, Lord Ashburton, and the British Minister in Washington, Mr. Fox. The British demanded the release of McLeod on the basis that he was acting on behalf of the British government and should therefore not be held individually responsible,51 while the U.S. sought an apology for the incident. The communications concluded in 1842.
The main disagreement concerned the facts, including whether it was necessary to attack at night while people slept, to set fire to the vessel, and then to cut the moorings. However, both States agreed on the legal principles to be applied, including the “inviolable character of the territory of independent nations”.52 They also agreed that a violation of this principle would be defendable if based on “a necessity of self-defence, instant, overwhelming, leaving no choice of means, and no moment for deliberation”.53 The importance of the Caroline affair is therefore that it shifted self-defence “from a political excuse to a legal doctrine”,54 and set out the requirements for lawful self-defence.
State practice in the years before the UN Charter was drafted confirms the existence of a right of self-defence in customary international law. For instance, in 1929, States were asked by the Preparatory Committee of the Hague Conference of 1930 on the Responsibility of States for Damage Caused to the Person or Property of Foreigners to respond to the following question: “Circumstances in which a State is entitled to disclaim responsibility. What are the conditions which must be fulfilled: ‘When the State claims to have acted in self-defence’?”.55 Although not the topic for the conference, some of the replies of the States confirmed their belief in a legal right of self-defence when faced with an unlawful attack by another State.56 Similar statements were made by States in 1931 regarding the potential amendment of the League of Nations Covenant in light of the Kellogg-Briand Pact, both in response to a questionnaire sent out by the Secretariat and in debate in the First Committee of the League of Nations Assembly.57
[i]t is clear that when the plans for an attack on Norway were being made, they were not made for the purpose of forestalling an imminent Allied landing, but, at the most, that they might prevent an Allied occupation at some future date. (…) Norway was occupied by Germany to afford her bases from which a more effective attack on England and France might be made, pursuant to plans prepared long in advance of the Allied plans which are now relied on to support the argument of self-defense.61
The right of self-defence was also confirmed in the so-called Ministries Case, where the Nuremberg Tribunal stressed that “he who initiates aggressive war loses the right to claim self-defense”.62
In the trials before the Tokyo tribunal, Japan also relied on self-defence as a defence against the charge of waging a declared or undeclared aggressive war against France, the Netherlands, Great Britain and the United States of America.63 The Tribunal emphasised that “[a]ny law, international or municipal, which prohibits recourse to force is necessarily limited by the right of self-defence”,64 but held that the facts did not satisfy its requirements. In relation to the Netherlands, for instance, the Japanese self-defence claim was based on the declaration of war by the Netherlands on Japan, but the Tokyo Tribunal held instead that the Dutch declaration was a form of anticipatory self-defence to protect Dutch colonies in the East Indies.65 Japan had been subjected to an oil embargo by the U.S. and Netherlands after its invasion of China, and the Dutch East Indies would provide an alternative source for oil. The Japanese attack was therefore considered imminent.
As these examples illustrate, sometime between the 1920s and the end of the Second World War the right of State self-defence as it is known today had crystallised in customary international law.66 The crystallisation took place despite the absence of an international agreement regarding the corresponding definition of aggression or prohibition on the use of force.67 Although the current customary rule for State self-defence has evolved and become more explicit with the development of the UN Charter and the prohibition and exception set out in Articles 2(4) and 51, the basic principles of necessity, proportionality and immediacy are still adhered to. In particular, where the application of Article 51 is not clear, it is interpreted in light of the customary rule.68
The Court therefore finds that Article 51 of the Charter is only meaningful on the basis that there is a “natural” or “inherent” right of self-defence, and it is hard to see how this can be other than of a customary nature, even if its present content has been confirmed and influenced by the Charter. Moreover the Charter, having itself recognized the existence of this right, does not go on to regulate directly all aspects of its content. For example, it does not contain any specific rule whereby self-defence would warrant only measures which are proportional to the armed attack and necessary to respond to it, a rule well established in customary international law. Moreover, a definition of the “armed attack” which, if found to exist, authorizes the exercise of the “inherent right” of self-defence, is not provided in the Charter, and is not part of treaty law. It cannot therefore be held that Article 51 is a provision which “subsumes and supervenes” customary international law.69
As the icj quote above emphasises, the content of the customary rule has evolved under the influence of Article 51. The details of the current right of States to use force in self-defence are, however, still subject to debate.70 One of the causes for debate is the question whether the two rights of self-defence, namely the customary right and Article 51, exist in parallel.71 While some argue that Article 51 set aside the pre-existing rule, so that any use of self-defence by States must be in accordance with the requirements set out in the UN Charter, others argue that the inherent customary right remains, with the result that self-defence for instance is not limited to armed attacks.72 Other major debates concern the questions of anticipatory self-defence and the use of force in self-defence in response to attacks by non-state actors. It is, however, difficult to perceive that a customary right of self-defence could be applied if it is incompatible with Article 51. The current relevance of the customary right is therefore the additional clarifications provided by the Caroline principles of necessity, proportionality, and immediacy.73
Because the relevance of State self-defence to this book is primarily contextual, the following presentation of current criteria for State self-defence is merely intended to be an overview of central issues.
6.2.3 Current Criteria for State Self-Defence
The use of force in State self-defence will first of all require that there be an ongoing or imminent armed attack against the State in question.74 There has been some debate on the threshold of armed attack, and whether armed attack must be distinguished from lesser forms of use of force. According to the icj, however, “Article 51 of the Charter may justify a use of force in self-defence only within the strict confines there laid down. It does not allow the use of force by a State to protect perceived security interests beyond these parameters”.75 Furthermore, the icj has expressed that a distinction must be made between an armed attack and for instance mere frontier incidents.76
Another topic that has been hotly debated by both States and scholars, especially in the aftermath of 9/11 attacks, is whether an attack must have been initiated before the State may use force in self-defence, or whether so-called preventive, anticipatory or pre-emptive self-defence (terms to which different commentators attribute different meanings) is permissible.77 Even though Article 51 makes reference to “if an armed attack occurs” (emphasis added), few would require a State to take the first blow before defending itself. As Dinstein points out, “‘if’ does not mean ‘after’”.78 Nonetheless, there are limits to how far in advance a threat may be averted by using force. To continue Dinstein’s clear distinction; “it also does not mean ‘before’”.79 The attack must be imminent, meaning that the threat of attack must be credible and there are no realistic alternatives to using force to avert the attack.80 According to the Caroline test, in order for force in self-defence to be permissible, there must be “no choice of means and no moment for deliberation”.81 This imminence requirement has particularly been challenged in the context of transnational terrorism. The use of unconventional methods means that the concrete attacks are rarely foreseeable. If an attack is considered highly likely, non-forceful means are exhausted or unavailable, and the use of force is the last chance to effectively defend against it, it is argues that self-defence should be permissible, even if it may be deemed anticipatory.82
It has also been debated whether the attack must be launched by a State, as opposed to a non-State actor, such as a terrorist group acting transnationally. Traditionally, the jus ad bellum right of self-defence has been viewed as permitting forceful response to attacks by another State.83 However, in the aftermath of the 9/11 2001 attacks on the United States, the immediate response from the UN Security Council (Resolution 1368 of 12 September 2001) was to condemn the attacks and recognise the inherent right of self-defence.84 The United States declared in October that they would take measures in self-defence against Al-Qaeda in Afghanistan,85 and other States made declarations of the intention to act in collective self-defence.86 When the Security Council in November of 2001 encouraged Member States to contribute to the efforts to fight terrorism in Afghanistan,87 States responded by declaring that they would support the United States in collective self-defence.88 Subsequent Security Council resolutions continued to make reference to self-defence. Although some claim that responsibility for the attacks could be attributed to the Taliban government of Afghanistan, there was limited evidence to support this claim.89 As a result, State practice appears to recognise the ability to act in self-defence against non-State actors.90
Nonetheless, in 2004, the icj took a very different approach. In its Advisory Opinion on Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, the Court stated that Article 51 “recognizes the existence of an inherent right of self-defence in the case of armed attack by one State against another State. However, Israel does not claim that the attacks against it are imputable to a foreign State”.91 This apparent limitation to attacks by States was, however, criticised in the Separate Opinions of Judge Higgins92 and Judge Koojimans,93 and in the Declaration by Judge Buergenthal.94 It was also criticised in the Separate Opinion by Judge Simma in the case of Congo v. Uganda,95 and is considered to have “wrongly ignored the effect of recent state practice on the law of self-defense”.96
Despite the position of the icj, States continue to apply self-defence in response to non-State actors, as illustrated by the response to the terrorist attacks by the non-State actor the ‘Islamic State in Iraq and the Levant’ (isil, also known as Da’esh).97 Several States have fought against isil on Syrian territory, and have notified the UN Security Council of their collective self-defence actions in support of Iraq, pursuant to the requirements set out in Article 51.98 Interestingly, while the United States explained that Syria was considered “unwilling or unable to prevent the use of its territory for such attacks”,99 not all States have expressly dealt with the fact that they are operating within another State’s territory without the consent of that State.100 The “unwilling or unable” doctrine is, however, outside the scope of this book.101 Lastly, it should be noted that the use of force in self-defence is limited to attacks originating from outside the territory of the attacked State. Domestic terrorism is a matter of law enforcement, unless the actions of the terrorist group may be imputed to another State.102
A final issue regarding armed attack is whether self-defence permits States to rescue nationals under threat in another State when the latter State does not consent to a rescue operation. The main question here is whether it is sufficient that the armed attack is directed against nationals abroad rather than the territory of the State.103 While it could be contended that a right of intervention to protect nationals derives from customary international law independently of self-defence, the typical view is that such an approach would be less satisfactory than invoking self-defence.104
When the requirement of armed attack has been met, the attacked State may consider the appropriate way to deal with the attack. States can act in self-defence individually or with the support of other States in collective self-defence, as the case of isil illustrates. If States are acting in collective self-defence, as in the case of nato pursuant to Article 5 of the North Atlantic Treaty, the attacked State must have requested the support of other States.105
Whether the defensive action is undertaken unilaterally or in cooperation with other States, the first requirements that must be bet to qualify the action as self-defence is whether the use of force to counter the attack is necessary. The use of force is a measure of last resort and it is therefore required that it would not be possible to defeat an ongoing, or deter an imminent, armed attack by other means.106 Necessity thus demands that non-forceful alternatives are exhausted or unavailable.107
Some have argued that the principle of necessity requires verification that the attack in question is intentional.108 Although it is unlikely that a single missile accidentally fired across a border or armed troops unintentionally crossing an international border will make the use of force in response necessary, it will in many cases be difficult to ascertain whether an attack was intentional or not. It would therefore be problematic to require the verification of intention before acting in self-defence. Furthermore, even if the armed attack is not intentional, it should still be legitimate for the attacked State to defend against it if the use of force is otherwise considered necessary.109 In practice, however, it is likely that an unintended attack is quickly brought to an end when the mistake is uncovered, making further use of force in self-defence superfluous and unnecessary.
Once it is established that the use of force is necessary, the question of how much force may be used is a matter of proportionality.110 Proportionality does not require equality in size, duration or form between the defensive action and the initial armed attack.111 Instead, the defence must be in proportion to the purpose of the use of force, namely to halt and repel the armed attack.112 In other words, it must be reasonable.113 If the defensive action is more extensive or harmful than the armed attack that provoked it, it could be perceived as unreasonable, and would therefore require careful justification.114 This jus ad bellum principle of proportionality must be distinguished from the jus in bello or loac principle (dealt with in Section 4.3). In the latter case, the principle refers to the correlation between expected incidental civilian losses (‘collateral damage’) and the anticipated concrete and direct military advantage arising from an attack.115
Although closely linked to necessity, immediacy is commonly listed as a separate criterion. While the imminence requirement referred to above describes the threat of attack and the ability to act in anticipation of a future attack, immediacy entails a temporal limitation on the defensive action. It must not be punitive in character.116 As a result, the use of force in self-defence must be “neither too soon nor too late”.117 In the Nicaragua case, for example, the icj explained that the U.S. actions against Nicaragua could not be seen fulfilling the necessity requirement when they took place several months after the major offensive against El Salvador on whose behalf U.S. contended to act in collective self-defence.118 Importantly, this standard does not appear to be applied in an overly literal manner.119 It is, for instance, accepted that it may take time to prepare the response, as was the case in the Falkland Island Wars of 1982.120 Furthermore, in the context of terrorist attacks, the fact that they had the capability and intention to attack once will in many cases be a strong indication of future attacks being likely as well, with the result that the use of force in self-defence will be both in reaction to a previous or ongoing attack and in anticipation of future attacks.121
Finally, when acting under UN Charter Article 51, there is a requirement to report immediately to the UN Security Council, as the abovementioned letters from States to the UN Security Council in relation to Al-Qaeda and isil illustrate. In addition, States must cease to use force when the Security Council has taken measures to maintain international peace and security. However, as Aust points out, “[a] measure which may look good on paper, but does not protect the State attacked, cannot legally stop the State using force in self-defence.”122 The measures taken by the Security Council must actually have the effect of restoring or maintaining international peace and security for a State to lose its right to use force in self-defence. If a State fails to report to the Security Council, this may be taken as an indication that it did not at the time consider its use of force to be in self-defence.123
6.2.4 The Distinction between State and Personal Self-Defence in Practice
For military forces, State self-defence is mainly relevant in situations not already amounting to an armed conflict or in relation to actors not party to the ongoing conflict. As explained in Section 4.3, while the jus ad bellum, including State self-defence, regulates the use of force that initiates an armed conflict, once an armed conflict has begun, the continued use of force is primarily regulated by the law of armed conflict, with personal self-defence as an additional option in exceptional circumstances. The use of force in State self-defence is, and should be, a political decision. As emphasised by Boddens, “it is not up to the individual serviceman, regardless of his or her rank, to determine whether actions taken by the armed forces or agents of another State necessitate a response on the basis of national self-defence unless he or she has been explicitly and clearly authorized or ordered to do so by the national (political) command authorities”.124 Furthermore, it is important that the public international law concept of self-defence is distinguished from the criminal law concept.125
If military forces are operating in the vicinity of a hostile State, for instance due to the position of their aircraft or vessel, or if land forces are operating on or near a border of a hostile neighbouring country, they should be given the instructions on how to respond to an attack or threat of attack, including use of force. The use of force may be justified on the basis of self-defence; the question is which self-defence type they apply. Because the threat is both to the troops and to the State they represent, their right of personal self-defence will be closely related to the authority to defend their State and the State’s right to use force under Article 51. Although both legal bases will permit some form of defensive actions to be taken, the purpose for the use of force will differ and thus affect how they respond. It may be possible to avoid the threat to the troops concerned without using force; however, this would not necessarily remove the threat to the State. Furthermore, the amount of force would be defined not only by what would halt and repel an attack on the troops in question, but if necessary also an attack on their State. It is therefore likely that the force they would be permitted to use in State self-defence would be more significant than in personal self-defence: the object intended to be protected will affect the assessment of what is necessary and proportionate use of force.
The two forms of self-defence are unlikely to be assessed simultaneously. Their personal right of self-defence would be relevant in a criminal case concerning the death or injury the military forces caused when defending themselves. As will be explained in Section 6.3, it is a defence that relieves an individual of responsibility for an act that would otherwise constitute a crime of murder. The exercise of State self-defence, on the other hand, would only be examined if the State is accused of violating Article 2(4), and the military forces may be tried for their involvement in and individual criminal responsibility for this crime.126 It is, in other words, a defence relevant to the crime of aggression, a crime that will likely only be tried by an international tribunal, and the accused would probably be political and military leaders. These would be tried as individuals for acts performed in their official capacity.127 The practical importance of the distinction therefore lies in the need to know what is being defended and as a result, what type and amount of force may be used.128
6.3 Personal Self-Defence
6.3.1 Personal Self-Defence in International Law: an Inherent Right?
6.3.1.1 Introduction
Is there an international law concept of personal self-defence common to all (nato) States? Because national approaches to self-defence are similar but nonetheless differ, such an international concept would promote a common understanding of self-defence and therefore improve interoperability. In order for personal self-defence to exist in international law, it must according to Article 38(1) of the icj Statue be derived from either treaty law, customary law or be a general principle of international law.129 There are no international treaties explicitly recognising a general right to personal self-defence.130 The only implicit recognition of such a right is found in Article 31 of the Rome Statute to the International Criminal Court and Article 2(2) of the echr.131 These will therefore be considered first, before examining whether there is a concept of personal self-defence in international customary law or as a general principle of international law. The only reference to self-defence in loac is in relation to acts not causing protected persons to lose their protected status,132 and self-defence is generally not considered to be regulated by loac.133 loac will therefore not be considered in this section.
6.3.1.2 International Criminal Law
a person shall not be criminally responsible if, at the time of that person’s conduct (…):
(c) The person acts reasonably to defend himself or herself or another person or, in the case of war crimes, property which is essential for the survival of the person or another person or property which is essential for accomplishing a military mission, against an imminent and unlawful use of force in a manner proportionate to the degree of danger to the person or the other person or property protected. The fact that the person was involved in a defensive operation conducted by forces shall not in itself constitute a ground for excluding criminal responsibility under this subparagraph.135
The Rome Statute has not achieved universal ratification, even among nato States. However, the concept of self-defence codified in the Rome Statute was not new.136 The significance of the provision is that it confirms the existence and applicability of the defence to international criminal law (icl), and most importantly provides the applicable criteria. It is thus a useful starting point when examining personal self-defence in an international context.
Before the Rome Statute came into force, courts considering self-defence in an icl context looked to domestic criminal law for guidance.137 Self-defence was, for instance, raised as a defence in some of the post-Second World War trials. The respective tribunals accepted the legal applicability of the defence, but in most cases the defence was denied on the basis of the attendant facts.138 A rare example of self-defence being pleaded successfully was in the trial of Erich Weiss and Wilhelm Mundo. The accused were German policemen who had shot and killed a prisoner of war because they thought he was about to shoot them. They were believed and acquitted.139 There is no written rationale for the Court’s judgement, but the UN War Crimes Commission commented that “[t]he finding of the Court is evidence that self-defence which, according to general principles of penal law is an exonerating circumstance in the field of common penal law offences when properly established, is also relevant, on similar grounds, in the sphere of war crimes”.140
Self-defence was also pleaded before the icty in Prosecutor v Kordic and Cerkez, but was rejected.141 The importance of the case is the willingness of the icty Trial Chamber to consider the defence, even though the Statute of the International Tribunal does not provide for self-defence as a ground for excluding criminal responsibility. It was the view of the judges that defences, even though not contained in its Statute, “form part of the general principles of criminal law which the International Tribunal must take into account in deciding the cases before it”.142 The Trial Chamber went on to cite Article 31(1)(c) of the Rome Statute, which was viewed as reflecting “provisions found in most national criminal codes and may be regarded as constituting a rule of customary law”.143
Article 31(1)(c) sets out several criteria for when and how force may lawfully be used in self-defence. First, it requires the existence of an imminent and unlawful use of force. This has been interpreted by Albin Eser to mean “immediately antecedent, presently exercised or still enduring”,144 and may according to Kai Ambos include both “physical coercion and psychological threats”.145 Furthermore, this threat or use of force must itself be unlawful. This excludes the possibility of relying on self-defence in response to the use of force by persons authorised to use that force, such as police officers carrying out a lawful arrest or combatants attacking a lawful target as defined by loac.146 The impact of the requirement of the initial use of force being unlawful is further elaborated on in Section 8.2.3, but it should be emphasised here that it only excludes the application of self-defence. Other legal authorities for using force may still apply, particularly the combatant privilege to participate in hostilities and carry out lawful acts of war.147
There was some debate during the negotiations of Article 31 of whether it would be sufficient that the actor ‘reasonably believed’ there to be an imminent danger, but this approach was not adopted. Instead, the objective standard of ‘acting reasonable’ was applied. According to McCormack, a consequence of choosing this test is that “[i]f the objective test of reasonableness is not satisfied on the facts of a particular case but the accused held a genuine belief that it was necessary to act as he/she did in self-defence, the appropriate defence may well be mistake of fact rather than self-defence”.148
In other words, the objective test makes it more difficult to make a successful plea of self-defence. Meeting the objective standard is, however, not sufficient. Although it is not specified in the statute, the generally recognised requirement of defensive intent is also considered applicable to an assessment of the legality of use of force in self-defence pursuant to Article 31(1)(c).149 According to Eser, this is implied by the formulation ‘to defend’.150 This entails that the force must be used with the intention of repelling the attack, if not exclusively then at least partially.151 Phrased differently, the defender must be acting in good faith, believing him – or herself to be entitled to use force in self-defence.152
Pursuant to Article 31(1)(c), self-defence may be relied upon in defence of three categories: the accused person; another person; or, in the case of war crimes, “property which is essential for the survival of the person or another person or property which is essential for accomplishing a military mission”.153 With regards to persons, force may be used to protect life, physical integrity and liberty.154 The inclusion of defence of property was perhaps the most controversial aspect of the provision. The concern appears to have been two-pronged. First, some States have national legal systems that do not permit the use of lethal force in self-defence to protect property. Second, there is concern that the justification for using lethal force in order to protect property goes too far. Therefore, although property was included as an object of protection on the basis of proposals by the United States and Israel, the protection was limited to “property which is essential for the survival of the person or another person or property which is essential for accomplishing a military mission” and is only a defence to war crimes.155 Among those critical of this aspect of Article 31(1)(c) was Cassese, who claims “it unjustifiably departs from customary international law, which (…) only affords self-defence as a justification for saving life and limb of the person acting in self-defence or other persons whose life and limb was in imminent danger”.156 As a result, while protection of property essential for a person’s survival may be generally recognised as an aspect of self-defence of persons, the use of self-defence to protect mission essential property probably remains controversial.157
In reality, the potential for claiming a defence of property is very limited. First, the objective must not only contribute to the accomplishment of the mission, it must indispensable (“essential”).158 Furthermore, it is only available in the context of war crimes, and there is no general prohibition on attacking “property which is essential for the survival of the person or another person or property which is essential for accomplishing a military mission”, unless it amounts to an attack on objects indispensable to the survival of the civilian population.159 The attack would therefore have to be otherwise unlawful, for instance because it involves the use of unlawful means, or it causes excessive incidental loss of civilian life, injury to civilians, damage to civilian objects.160 Proportionality (i.e. loac type) is, however, difficult to assess without having further knowledge of the military advantage sought to be achieved.161 The scope for using self-defence to defend property is also limited by the self-defence requirement of proportionality. As will be further explained in the next paragraph, self-defence proportionality requires the damage to the aggressor not to exceed the danger to be averted, and the object protected will need to particularly important in order to justify killing an aggressor to defend it.162 Finally, the reference to “essential for accomplishing a military mission” may be read as a reference to military necessity in loac. However, unlike the use of force permitted on the basis of military necessity in loac, defence of objects under article 31(1)(c) is limited to those that are under threat of unlawful attack.163
Irrespective of which of the above categories is defended, the use of force in response to the threat must be reasonable. The requirement of reasonableness entails that it must be both necessary and suitable, in that it must be needed to divert the attack and must not be “inapt by implying ineffective or otherwise futile means”.164 In addition, the degree of force used must be proportionate to the danger faced. For instance, it will only be admissible to kill the aggressor in order to avoid death or serious bodily harm.165 This was emphasised in three cases considered by the icty in Gotovina and others. The Trial Chamber rejected the claim that the perpetrators responded to an imminent unlawful attack, but went on to stress that even if there had been such an attack, the response would have been disproportionate, as there were “other ways of thwarting any possible danger instead of firing lethal shots”.166
Finally, Article 31(1)(c) emphasises that involvement in a defensive operation conducted by forces is not in itself a ground for excluding criminal responsibility as lawful self-defence. The sentence of the provision started off as a footnote to register the concerns of some delegations that the definition of self-defence could be interpreted too widely.167 Unfortunately, it is not entirely clear what is meant by this final sentence. A potential source of confusion is the reference to ‘defensive operations’, which may have different meanings depending on the context.168 It may both be a reference to State self-defence and to forces involved in an ongoing armed conflict undertaking a defensive operation regulated by loac.169 However, it is clear from the commentaries to Article 31 that the intention behind the reference is to emphasise that the use of force in self-defence by individual soldiers against an unlawful attack on themselves, others or certain objects, is not regulated by or affected by the application of State self-defence.170 The last sentence of Article 31(1)(c) is therefore a reminder that Article 31 remains the applicable legal framework for assessing self-defence regardless of the general nature of the operation.171 As Eser explains, it makes it clear that “‘private self-defence’ (…) is not privileged only because its operational framework is legal [according to public international law], nor is it is it foreclosed only because the operational context is illegal”.172 It is an important reminder that the “ius ad bellum and actio in bello are to be kept distinct”, rather than be conflated.173
The negotiations over Article 31(1)(c) also raised the issue of voluntary exposure, that is, when the person claiming to have acted in self-defence voluntarily exposed him – or herself to the threat or attack. A footnote in a draft version of the article emphasised that “voluntary exposure is not understood to constitute a basis for applying the provisions concerning self-defence”, but in the end it was determined to be an issue for the Court to consider under Article 31(2).174 The effect of self-exposure on the application of self-defence in general is considered further in Section 8.2.4.
The purpose of the icc is to ensure that “the most serious crimes of concern to the international community as a whole must not go unpunished”.175 The icc therefore only has jurisdiction over war crimes, crimes against humanity, genocide and as of 17 July 2018, aggression.176 As many commentators have pointed out, the relevance of self-defence is therefore likely to be minimal.177 In particular, it seems unlikely that a crime against humanity or genocide can be justified by reference to self-defence. According to McCormack, “[i]t is the nature of these two offences that raises scepticism as to the possibility of exclusion of criminal responsibility on grounds of self-defence. Both categories of crimes require a quantitative threshold for multiple victims and involve the wilful targeting of civilians. War crimes, in contrast, require no quantitative threshold – they can involve single isolated acts with single victims”.178 For the crime of aggression, the relevant self-defence concept will be State self-defence, not personal.
Despite the potentially narrow scope of application of both icc jurisdiction in general and the icc self-defence provision in particular, Article 31(1)(c) likely reflects the general international understanding of the concept of personal self-defence. It accordingly seems safe to conclude that in the context of icl, personal self-defence is a general principle of law which an international criminal court may take into consideration.179 As a result, if a case of icl arises before an international court or tribunal other than the icc, and self-defence is not regulated in the instrument outlining the court’s competence, then that court may rely still rely on self-defence as a ground for excluding criminal responsibility.180 Furthermore, it is likely that it will look to Article 31(1)(c) and any relevant icc case law as the only formalised international expression of this rule, as was done by the icty in the Kordic and Cerkez case.
6.3.1.3 International Human Rights Law
As mentioned above, personal self-defence is only implicitly recognised in human rights legislation. In Article 2(2) of echr, the concept of self-defence is referred to as a lawful exception to the prohibition: “Deprivation of life shall not be regarded as inflicted in contravention of this Article when it results from the use of force which is no more than absolutely necessary: (a) in defence of any person from unlawful violence”.181 The use of force in self-defence is in other words not arbitrary and hence not prohibited. The prohibition on arbitrary deprivation of life in Article 6 of iccpr is interpreted to also permit the use of force in self-defence.182
Self-defence appears to challenge ihrl. On its face, it violates one person’s right to life in order to protect another’s right to life. Because self-defence is an important instrument in protecting life, some have claimed that it is itself a human right.183 This argument has, inter alia, been made by proponents of a right to keep and bear arms.184 The question whether self-defence is a human right was therefore addressed in the UN report on ‘Prevention of human rights violations committed with small arms and light weapons’.185 The conclusion is that self-defence is not a human right but rather a means of protecting the right to life and, as such, a basis for avoiding responsibility for violating the rights of another.186 This seems to be the correct conclusion. As Boddens-Hosang points out, the right to life no more creates a corollary right to use force in self-defence than the right to freedom of speech grants a right to force the media to publish one’s views.187 Furthermore, neither international treaties nor national practice suggest that States view personal self-defence as a human right.188
The better approach is therefore that the right to life is a human right, while self-defence is ‘merely’ a permissible exception to this right vis-à-vis others and a way of protecting the right to life of the person acting in self-defence. According to Hessbruegge, “[h]uman rights shape the right to self-defense because they prohibit denying or unduly curtailing the right to personal self-defense. In this sense, the right to personal self-defense is a derivative of human rights, even if it is not a human right itself”.189 This means that it obliges States through their courts to take into consideration whether there are extenuating circumstances such as self-defence when a person is accused of homicide.190 In addition, ihrl impose procedural and substantive restrictions on the use of force, in particular by State actors such as law enforcement officials and military forces.191 By contrast, because it is not human right, States are not obliged to secure the right to use force in self-defence for instance by providing the means to engage in it or by refraining from imposing excessive restrictions on access to such means, such civilian access to weapons.192
In the context of military forces using force in self-defence, the responsibility of the State is to ensure that extenuating circumstances such as self-defence are considered if a soldier is accused of and tried for murder. The details of self-defence are set out in domestic legislation,193 but must not be construed more widely than the exception in Article 2(2) of the echr,194 or in the case of other human rights conventions, the interpretation of accepted exceptions to the right to life. Furthermore, as will be discussed in Section 8.2.10.2, the fact that personal self-defence is not a human right also entail that States may impose limitations on that right, for instance through roe or other forms of military orders.
A final issue that should be mentioned is that protection of property is not included in the exceptions listed in Article 2(2) of the echr. Similarly, property is not considered an acceptable object of protection by lethal means under the iccpr.195 This means that States whose domestic legislation permits the use of force in defence of property ought to limit this to situations in which a threat to life or limb is involved.196
6.3.1.4 Customary International Law and General Principles of International Law
Personal self-defence is also argued to be part of customary law, perhaps most notably by the icty in the Kordic and Cerkez case,197 as cited above in Section 6.3.1.2. As explained in Section 1.4, customary international law development requires the existence of State practice accompanied by an acceptance that the practice is required by international law (opinio juris sive necessitatis).198 The concept of lawfully defending oneself is clearly historic, thoroughly entrenched, and seemingly universal in its inclusion in domestic legislation. In fact, comparative studies have not identified a single domestic legal system not recognising self-defence.199 However, this does not necessarily mean that States view it as anything more than a national rule they may change if they see fit.
Although the universal recognition of self-defense in domestic law could amount to state practice for the development of a customary rule, this has been convincingly rejected on the basis that the prerequisite opinio juris is lacking. Hessbruegge, for instance, has asserted that “[i]n many cases, legal recognition of the right to self-defense even predates the existence of the states applying them. It would therefore amount to pure fiction to presume that states have recognized the right to personal self-defense in their domestic legal orders out of a sense of being required to do so by international law”.200 The same conclusion is reached by one of the few other commentators on the topic, Cerone.201 If the State practice of recognising personal self-defence is not influenced by the belief that it was required by international law, it appears to be an unlikely candidate for a general customary international law rule, that is, beyond the context of icl.202
There is therefore a law, gentlemen, not one written down anywhere but a natural law, not one that we have learned, inherited, and read, but one that we have seized, imbibed, and extracted from nature herself, a law for which we were not taught, but made, which we know not from instruction but from intuition, the law which states that, if any attempt is made upon our lives, if we encounter violence and weapons, whether of brigands or enemies, then every method of saving ourselves is morally justifiable. When swords are drawn the laws fall silent; they do not require you to wait for them, because the man who chooses to wait will have to pay an undeserved penalty before he can exact a deserved one.204
Similar views on self-defence are also presented by subsequent writers. Aquinas (1224–1275), for instance, explained that “since one’s intention is to save one’s own life, [self-defence] is not unlawful, seeing that it is natural to everything to keep itself in ‘being’, as far as possible”.205 Gentili (1552–1608) declared that “one who is attacked by an armed enemy makes a necessary defence, and his action is that of necessary defence; and so also does one against whom an enemy has been making preparations” (…) “for to kill in self-defence is just”.206 According to Pufendorf (1632–1694), “nature at times allows the recourse to violence, when we cannot in any other way preserve our safety because of the aggression of another”.207 He goes on to explain that “when a man, contrary to the laws of peace, undertake against me such things as tend to my destruction, it would be a most impudent thing for him to demand of me that I should thereupon hold his person inviolate, that is, that I should sacrifice my own safety so that his villainy may have free play”.208 Of particular interest to the current topic is the contention by Vattel (1714–1767) that because self-defence “belongs naturally to every man” and therefore does not require permission, it is the only basis for the use of force by military forces in the absence of express orders.209 Blackstone’s 1769 Commentaries on the Laws of England similarly emphasised that because self-defence “is justly called the primary law of nature, so it is not, neither can it be in fact taken away by the law of society”.210 All major cultures and religions contain similar references to self-defence, even if they differ in how this right to use force is reconciled with the general prohibition on the use of force.211 For instance, while Islam views self-defence as a duty to prevent one’s own destruction, Buddhism views it as an act of compassion, both towards the victim and the aggressor who is prevented from killing another, which would have been an act of bad karma.212
The concept of self-defence referred to by these writers closely resembles that which we know today. For instance, Aquinas explained that lawful self-defence required defensive intent, proportionate use of force, and necessity. As the quote above indicates, the use of force with the intention to save one’s own life is not unlawful. He also explained that “though proceeding from a good intention, an act may be rendered unlawful, if it be out of proportion to the end. Wherefore if a man, in self-defense, uses more than necessary violence, it will be unlawful: whereas if he repel force with moderation his defense will be lawful, because according to the jurists, ‘it is lawful to repel force by force, provided one does not exceed the limits of a blameless defense’”.213 Furthermore, Grotius proclaimed that in order for the use of force in self-defence to be lawful, “[t]he danger (…) must be immediate and imminent in point of time”.214 He elaborates by explaining that “if a man is not planning an immediate attack (…) he cannot lawfully be killed, either if the danger can in any other way be avoided, or if it is not altogether certain that the danger cannot be otherwise avoided”.215
European practice in the Middle Ages and early modern period was to suppress forms of self-help in order to consolidate the power of the sovereign rulers and establish a state monopoly on the use of force.216 It is therefore not surprising that those seeking to set out a right of self-defence during that period looked to natural law. For instance, the first recognition of self-defence in English common law was in a law passed in 1532, while the right was not incorporated in France until 1791.217 Although the question whether self-defence originates from and is currently based on natural law or positive law in the form of domestic law is interesting, the more relevant question in the current context is whether the universal recognition of self-defence illustrated by these quotes indicates that personal self-defence is a general principle of international law.218
General principles of international law were intended to avoid a non liquet, (a situation where there is no applicable law) without having to allow the International Court of Justice (icj)219 to legislate.220 According to Cassese, however, it is more realistic that general principles are applied to solve a conflict between two or more applicable conventional or customary rules.221 Article 38(1)(c) allows the icj to deal with a situation not regulated by treaty or custom by looking to “rules accepted in domestic law of all civilized states”222 for guidance. Although it has been suggested that Article 38(1)(c) contains natural law elements,223 the icj is bound by Article 38, and is therefore unable to rely on natural law as an independent source of general principles of international law. As Pellet explains, “the existence of a ‘natural law’ principle of this kind cannot be appreciated subjectively by the Court, it must be attested by its recognition in domestic laws”.224
It is sufficient that a general principle provides “general guidelines which then have to be applied by the Court”.225 Personal self-defence is clearly an accepted rule in domestic law, and although some of the details vary, the idea is the same. It should therefore be capable of providing general guidance. However, in addition to being “unwritten legal norms of a wide-ranging character” and “recognized in the municipal laws of States”, the general principles referred to in Article 38(1)(c) must be “transposable at the international level”.226 With the exception of icl, it is not clear whether personal self-defence fulfils these requirements.
While the icj rarely has relied expressly on general principles, they have been applied both by individual judges and by States.227 Examples of principles that have been considered as general principles include consent, good faith, equality, reciprocity, finality of awards and settlements, and the legal validity of agreements.228 In the context of icl, the icty has applied respect for human dignity as a general principle.229 As these examples illustrate, general principles tend to be of a significantly different character than personal self-defence; they are general in the sense that they apply to a wide range of legal issues. As Cerone explains, general principles “tend to be formulated in extremely general terms and as such operate in a residual fashion”. They “tend to be employed as gap-fillers and interpretational aids”.230 These are not descriptions that fit well with a right of personal self-defence.
Nonetheless, it is common to claim that personal self-defence is a general principle of international law. According to Ohlin, it is “uncontroversial that as a matter of comparative law all civilized nations allow defendants to plead self-defence in some form in domestic criminal prosecutions and that it is therefore a general principle of criminal law”.231 Hessbruegge similarly concludes that “[r]egardless of whether general principles of law under Article 38(1)(c) of the icj Statute derive from natural law or from universally shared features of domestic legal orders, the right to personal self-defense forms part of the corpus of these general principles”.232 In the aforementioned final report submitted by the Special Rapporteur on Prevention of Human Rights Violations Committed with Small Arms and Light Weapon, it is contended that “[t]he presence of the principle of self-defence in emerging international criminal law reflects the global uniformity of the principle of self-defence and its elements”.233
The universal and historic recognition of self-defence makes it unique. The fact that the criteria have not changed much since the time of Grotius or even Aquinas underlines the fundamental nature of the right. As Hessbruegge concludes, “[t]he right to self-defense is a genuinely pre-social right that evolved in the absence of the state. It survived the formation of the state because no state will ever have enough power to perfectly protect individuals”.234 The arguments that personal self-defence does amount to a general principle of international law are therefore not without merit, and are for instance supported by the recognition of self-defence as an exception to the personal inviolability of diplomatic agents.235
What, then, would the recognition of personal self-defence as a general principle of international law entail? If the recognition is going to have any meaningful impact, it must be enforceable. However, the use of force by individuals, including members of military forces, is most likely to be considered by national courts, on the basis of both domestic legislation and legal traditions. It seems unlikely that national judges would look to general principles of international law in cases under domestic criminal law. If the use of force during an armed conflict is examined by an international criminal court, the applicable self-defence rule will either be set out in the statute of that court, or be based on the abovementioned customary international law self-defence concept applicable to icl. Beyond this, there is limited scope of application of a general international law principle of personal self-defence. As a result, and as Hessbruegge admits, the recognition of personal self-defence under international law “may not make much of a difference in strictly legal terms”.236
The approach taken by nato Member States to self-defence in the context of roe further supports the prevalence of personal self-defence as domestic legal concept rather than a rule of international law. As explained in Section 2.2.1, nato roe does not regulate the use of force in self-defence because this is left for member States to define. The MC 362/1 nato Rules of Engagement states that “it is universally recognised that individuals […] have a right to defend themselves against attack or imminent attack”.237 However, it goes on to emphasise that in exercising the right of self-defence, “individuals and units will act in accordance with national law”.238 If a general principle of international law existed with regard to personal self-defence, it is likely that this would have been applied instead of domestic legislation. In fact, as a result of the different national approaches to self-defence, there are nato roe specifically developed to harmonise the ability of nato forces to use force in response to threats.239
6.3.1.5 The Existence and Relevance of an Inherent Right to Personal Self-Defence in International Law
Self-defence as a concept clearly exists in international law as a customary rule of State self-defence, codified in Article 51 of the UN Charter. Individuals, on the other hand, do generally not have legal personality under international law, and it is difficult to see how a general principle of personal self-defence could exist in a meaningful manner, that is, beyond the areas of international law that applies to individuals. Self-defence is referenced in ihrl, but only in connection with the primary rule of right to life. In icl, there is arguably a general principle of international law, or perhaps even a customary international law rule on self-defence. However, the application of that rule is limited to international criminal tribunals or courts. It would therefore only be relevant to nato forces in the case of a war crimes trial before an international tribunal.
In the context of international law, it may therefore be concluded that characterisation of personal self-defence as ‘inherent’ does not have independent legal implications. The application and the details of personal self-defence are defined nationally by domestic legislation, and there is therefore no unitary concept. As Henderson and Cavanagh explain, “it is the legislation and case law of a particular jurisdiction that gives meaning to the language and concepts within that jurisdiction, not the asserted legal basis”.240 Similarly, Nigel White concludes that “the detail [or] the framing of this natural right, is an issue for man-made law”.241 The only influence of international law on domestic self-defence rules is the obligations of States to ensure respect for the human right to life in the framing and enforcement of such rules.
Military forces must therefore expect any use of force in personal self-defence to be assessed on the basis of the applicable domestic legislation, primarily military justice codes, or criminal law such as the one set out in Section 6.3.2.3. If they are operating in another State with their consent, it is common to regulate questions concerning jurisdiction in a Status of Forces Agreement (sofa).242 As a result, if forces from State A are operating in State B, and a case arises where self-defence is asserted, it will be assessed on the basis of State A’s legislation, provided the matter is covered by the sofa. However, if they are not exempt from host nation jurisdiction, either because the act in question or the operation in general is not regulated by such a sofa, the self-defence applicable is that defined by the legislation of State B. Self-defence in State B may be defined differently than what forces from State A is familiar with from their domestic legislation. If a legally enforceable inherent right of self-defence applicable to all were to exist, State A could insist on a certain standard being applied. However, it is unlikely that State B would accept such interference with matters essentially within domestic jurisdiction.
If both the existence and application of an international principle of personal self-defence is unclear, why do roe tend to refer to ‘the inherent right of self-defence’? There appears to be two reasons: the historic or natural law origins of the right; and the influence of the formulation of State self-defence. First, the historic and customary origins of the right has caused common law countries in particular to formulate the domestic concepts as an inherent right (see e.g. self-defence in laws of England and Wales below). British, U.S. and Canadian traditions are likely have had a considerable influence the development of nato doctrines due to their sizeable contribution to nato and the language influence. In modern law, the perception of self-defence as inherent may also be influenced by the role of self-defence as a means of protecting the human right to life, which is considered one of the most fundamental human rights.243
Second, as alluded to in the introduction to this chapter, it may also seem that the reference to inherent in Article 51 made its way via jus ad bellum U.S. roe (proe) through the concept of ‘unit self-defence’ into personal self-defence regulated in roe for operations involving participating in armed conflict.244 As a result, the 2000 version and now current (2005) version of the U.S. sroe appears to rest its basis for both national and personal self-defence exclusively on the U.N. Charter. This reliance on the UN Charter for personal self-defence has correctly been deemed “misplaced”245 and “unsound”.246 When the nato roe were initially drafted, the U.S. roe were an important source of inspiration, and the reference to inherent right of self-defence may simply have been carried on. Finally, it has also been suggested that the reference to individual self-defence ad bellum self-defence, as defined in Article 51, may be a cause for confusion; when read out of context, ‘individual’ may be viewed as referring to persons, rather than individual states.247
6.3.2 Personal Self-Defence in Domestic Legislation
6.3.2.1 General Remarks
6.3.2.1.1 Applicable Law and Legal Requirements
nato has left it to the States participating in nato operations to define and regulate self-defence for their respective troops (as explained in Section 2.2.1.4). Although the reference to ‘inherent right’ may arise from natural law, which combined with the universal recognition of self-defence in domestic law may suggest that a general principle of international law pertaining to a right of personal self-defence exists, the conclusion in the previous section on personal self-defence in international law was that such a right is unlikely to be enforceable outside of icl.248 If the use of force in self-defence by a member of a nato force is subject to an investigation into individual responsibility for that act, this will be conducted by the troop contributing nation. As explained in Section 2.5, nations do not transfer disciplinary or penal jurisdiction over their forces, and only the most heinous crimes are considered by international criminal tribunals.
As a result, the domestic legislations of troop-contributing nations play a key part in defining when military forces detached to nato for a nato operation may use force in self-defence.249 Section 6.3.2.3 will therefore provide examples of how personal self-defence is regulated in a selection of nato Member States.250 As will be seen, most nato Member States do not have a separate military self-defence provision, with the result that the civilian criminal law concept is applied.251 Although there are differences in how States define and apply self-defence, the basic criteria are universally recognised.252
All domestic legal systems exclude criminal responsibility of individuals in the case of defence against an unlawful attack by another human being.253 The requirement that the initial attack is unlawful is particularly important in the current context because the use of force by combatants during armed conflicts is considered lawful acts of war.254 As a result, and as will be explained further in 8.2.3.2, where nato forces are faced with threats that originate from a lawful combatant, self-defence is not relevant because the attack is not unlawful.255 Otherwise unlawful acts in response to threats that are lawful will in peacetime or under domestic legislations generally be assessed on the basis of necessity considerations. This would for instance include breaking an entry into another’s house or steal a vehicle in order to escape from an aggressor. During armed conflict, however, necessity is exhaustively regulated by loac; loac is a particular form of necessity, especially developed for the unique situations that arise during an armed conflict.256 Necessity in the more general sense may therefore not be used as a justification for violating loac, and will not be dealt with further here.257
While some jurisdictions deal with all such defensive force, regardless of whom or what is attacked, as a single concept, others distinguish between defence of self, of others, and of objects. Common law countries have a tendency to have separate rules on the different subjects to be defended.258 Although the focus has traditionally been on the protection of self and others closely related to or under protection of the person using defensive force, it has expanded to include others more in general and to some extent objects.259 This distinction between the objects of protection is also reflected in the terminology used; the common law concept of self-defence only covers defence of self and to some extent defence of others.260 By contrast, civil law countries have traditionally been permitted to protect a wider range of interests, including property, and the challenge has instead been “to curtail the range of protected rights”.261 Rather than focusing on the interest protected, many civil law countries deal with self-defence as a general concept of necessary or legitimate defence.262 As the examples below illustrate, in many civil law countries, the term for self-defence is made up from the combination of two concepts: one entailing distress, emergency, or danger; and the other meaning to protect or defend. In practice, however, there is little divergence between States as to the core of the interests that may be protected; it is either life, physical integrity, physical liberty, or property.263
Domestic self-defence rules all require the defensive measure to be the least harmful way to prevent or stop the unlawful attack.264 Self-defence, therefore, is not only a justification applicable to the use of force; other defensive acts also need to be included, and will be required if lethal force can be avoided. The necessity requirement also affects the temporal scope of response; as mentioned in relation to State self-defence, it is generally recognised that the defensive act should be conducted “neither too soon nor too late”.265 Finally, all legal systems require the defensive act to be proportionate, meaning that it must not be grossly disproportionate to the harmful act.266 This is either formulated as a separate requirement or as part of the assessment of whether the use of force is reasonable or justifiable.
In addition to the objective criteria, self-defence is commonly considered to require “a particular mindset on the part of the person exercising it”.267 This requirement of defensive intent is intended to prevent the misuse of self-defence. Most jurisdictions apply a combination of a subjective and objective standard; the defendant’s acts are assessed on the basis of how he/she perceived the circumstances to be, but the defendant must, for instance, not have been reckless or negligent.268 This is sometimes formulated as a ‘reasonable man test’: would another person in similar circumstances have acted the same or similar way? Although there is a limit to the extent to which the reasonable man test should be adapted to the specific circumstances and the characteristics of the defendant, the unique circumstances of military forces, who are trained to kill and deal with high levels of threat, must be taken into consideration. This issue is examined further in 8.2.2. If the requirements of self-defence as not met, the defensive measure may still be fully or partially excused as a reasonable mistake.269
The reliance on personal self-defence as set out in domestic legislation during military operations also begs questions regarding jurisdiction and area of application. For operations that take place on the territory of the forces in question, the application of domestic criminal law will be unproblematic. However, although the military forces remain under the jurisdiction of their State even when operating in a different country, their criminal law may be subject to territorial limitations. Under the Norwegian Penal Code, for instance, Norwegian citizens not on Norwegian territory are only subject to Norwegian jurisdiction in relation to certain crimes.270 This includes, inter alia, serious crimes such as war crimes and other violations of loac. In addition, Norwegian authorities are able to prosecute acts that are criminalised by domestic legislation of the country in which they take place. As a result, if Norwegian authorities retain (for instance through a Status of Forces Agreement) or gain jurisdiction over a case arising abroad, a Norwegian soldier would be able to rely on self-defence as set out in Norwegian law. However, if Norwegian authorities do not have jurisdiction over the case and the prosecution takes place before the national courts in the State where the alleged crime was committed, the rules set out in the laws of the sending State will not apply.
6.3.2.1.2 Self-Defence as a Right
Self-defence is also commonly referred to both as a right and as a (criminal) defence.271 Although ‘criminal defence’ and ‘right’ may appear to be mutually exclusive characteristics,272 this does not necessarily need to be the case. According to Hessbruegge, rights (as opposed to liberties) are characterised as giving rise to a corresponding duty. Unlike other criminal defences such as duress, self-defence entails a duty on the receiver (attacker) to tolerate the defensive actions.273 For instance, a person who is inflicted injury or financial loss as the result of an act of duress may claim compensation, while an attacker has no right of self-defence against the defensive action. Personal self-defence may in other words be argued to operate both as a justificatory defence and as a right. According to comparative analyses of domestic law conducted by other scholars, most domestic legal systems consider self-defence to be a justification, and even where self-defence is not formulated as a justification, legislative bodies refer to it as a right.274
However, in order for the use of force in self-defence to be lawful, it must still fulfil the applicable requirements. Unless there is a domestic self-defence rule permitting the use of force in circumstances other than those set out in criminal law,275 the result of applying the two forms of self-defence, namely self-defence as a positive right or as a criminal defence, is likely to be the same. According to Gill et al., they may therefore be viewed as mirror images of each other.276
Self-defence will therefore be treated as a right and a legal basis for the use of force, founded on domestic (criminal) law.277 The reference to self-defence as a right should in other words not be read as entailing additional rights beyond those set out in the criminal law concept referring to a circumstance precluding wrongfulness. It is not a general right to use force, but one defined by its exceptional function as an officially sanctioned exception to the State monopoly on the use of force.278
6.3.2.1.3 Self-Defence as a Duty
Another area of discussion concerns the existence not only of a right of self-defence, but also of a duty or obligation to use force in self-defence. Although there may be a clear moral duty to help or to guard life,279 the question is whether and to what extent there is a legal duty to do so. It is not uncommon to have a legal duty to rescue someone in danger, especially if there is a relationship of trust or responsibility between the person in danger and those able to assist. This would be the case in the context of a school teacher and the school children, or of a health care worker and the patients. Similarly, in the case of traffic accidents, those who caused the accident and those who are first at the scene will, in accordance with some domestic legislation, have a duty to help. Furthermore, national law may require a person to try to stop a crime, including an unlawful attack, if doing so does not result in a risk of harm to the person helping or others.280 A duty to use force in self-defence would, however, in many circumstances involve a risk of harm for the intervening party. It seems therefore unlikely that there would be a general duty to use force in self-defence.
As explained in Section 4.2, ihrl require the State to respect and protect persons under its authority or control. As a result, even if there is no general duty to use force in self-defence, military forces have, because of their status as State agents, a duty to protect the lives of those subject to their State’s human rights jurisdiction and obligations, most importantly here the obligation to protect the right to life.281 Using force in defence of others, which in some jurisdictions is an aspect of self-defence,282 may be one way this duty is complied with. It is, for instance, clear that law enforcement officials have a duty to defend others, unless it would cause an unreasonable risk for those intervening,283 and this will arguably also apply to military forces in relation to persons under their State’s human rights jurisdiction. Furthermore, both law enforcement officials and military forces have a right to life and physical integrity, and the State will therefore have a duty to allow its agents to defend themselves.284 As a result, if a situation of self-defence arises in the context of operations involving participation in an armed conflict, the military commander will be obliged to do what is reasonable to effectuate such a defence.285
It may also be that military commanders have a duty to protect those under their command, beyond the scope of using force in self-defence. Such a duty is set out in the U.S. sroe, under the heading of “Inherent right of self-defense”, but only in the context of ‘unit self-defence’: “Unit commanders always retain the inherent right and obligation to exercise unit self-defense in response to a hostile act or demonstrated hostile intent”.286 ‘Unit self-defence’ is defined as allowing defence of other U.S. military forces in the vicinity. The emphasis on ‘unit self-defence’ as both a right and obligation is the result of incidents where it was perceived that the commanders could have done more to protect U.S. forces.287 However, as will be explained below in Section 8.3.3, ‘unit self-defence’ is more an operational concept or roe concept than a legal concept, and must therefore be distinguished from personal self-defence. A duty to use force in ‘unit self-defence’, if imposed on commanders, is thus based on the requirement to comply with the order to defend own forces rather than an obligation arising from the legal concept of self-defence. 288
6.3.2.2 Military Forces as Individuals and State Agents
Military forces are agents of the State, and will in that capacity have the authority to use force beyond what ordinary citizens are permitted to use.289 At the same time, military forces are also individuals with rights as citizens, and military forces retain certain rights as individual private persons even while they are State agents.290 They will be given the authority to use force to accomplish the mission, for instance within the framework of loac, but will always be able to use force in self-defence, provided the requirements are met. Although this scope for applying self-defence in practice differs for forces participating in an armed conflict, as compared to that applicable to private citizens,291 it nonetheless continues to exist.
Commentators differ in whether soldiers retain their rights as individuals when they become military forces and hence State agents, or whether the authorities provided by the State to use force replace the individual rights. For example, some argue that the use of force by military forces as part of their duties will be regulated by a form of ‘public authority’ doctrine, which will include loac and self-defence where applicable.292 Self-defence has also been argued to be part of the law enforcement paradigm,293 which may make it inapplicable to military forces participating in an armed conflict, unless they are specifically tasked with law enforcement duties in addition to their traditional military duties.
If the ‘public authority’ doctrine or equivalent authorities are subject to the peacetime use of force principles and limitations,294 including necessity, imminence, and proportionality, thereby restricting the ability to use force when there are less harmful alternatives and imposing a duty to use the least destructive or damaging means or method of defence,295 the result of applying such a doctrine will in practice be very similar to personal self-defence. However, there appears to be three main potential differences. First, the use of force will either be authorised or it is an otherwise unlawful act justified by way of being self-defence. Interestingly, Corn refers to his ‘public authority’ doctrine as a defence, implying that a defence remains necessary.296 In that regard, his ‘public authority’ doctrine does not differ from self-defence. Second, a justification for the use of force may relate to the private individual or to an act of State. As Corn explains, military forces are State actors, not private actors, and “[a]ligning self-defense authorities with public authority justification principles would (…) reduce servicemembers’ exposure to potential criminal jeopardy for their uses of force”.297 A ‘public authority’ defence would therefore remedy the concern that the use of force by military forces in situations arising from their duties have to be based on an individual or private right or responsibility, rather than being part of the authority to carry out their duties. Finally, while self-defence is a right that applies in exceptional circumstances and may only be used where there are no other alternatives, the use of force on behalf of the State under some form of ‘public authority’ doctrine could be pre-planned.
There are, in other words, advantages in applying a ‘public authority’ doctrine rather than personal self-defence to deal with threats arising outside the ambit of loac. However, although there perhaps ought to be the authority to use force in furtherance of official duties in all national legislation, this is not the case. A common approach is instead to declare that the use of force in accordance with international legal obligations such as loac will not entail a violation of national criminal law prohibiting those acts. If the use of force is not authorised by international law, it will be unlawful unless it is justified as self-defence.298 The approach taken in the current book is therefore that the use of force in self-defence must be based on the private criminal law concept. Admittedly, it would have been preferable if a ‘public authority’ concept, covering the use of force in those circumstances as well as for instance loac, existed and could be applied. However, this does not appear to be the current lex lata.
Finally, the status of military forces as State actors also introduces State responsibility for the force used. As explained in Section 4.2.2, the use of force not permitted by loac must be a measure of last resort. This requires training and planning to avoid unnecessary use of force and the availability of the means required to enable force escalation, obligations which rest upon the State.299 In addition, the State is obliged to investigate deaths resulting from the use of force by its representatives.300 Failure to comply with these obligations could give rise to State responsibility for the violation of the human rights of the victims, provided the use of force occurred on the territory of the State or the situation otherwise give rise to human rights obligations.301
6.3.2.3 Examples of National Rules on Personal Self-Defence
6.3.2.3.1 Danish Law
- 1)Acts committed in self-defence are not punishable if they were necessary to resist or avert an unlawful attack that has begun or is imminent, provided that such acts do not manifestly exceed what is reasonable with regard to the danger inherent in the attack, the aggressor and the importance of the interests endangered by the attack.
- 2)Any person who exceeds the limits of lawful self-defence shall not be liable to punishment if his act could reasonably be attributed to the fear or excitement produced by the attack.302
As mentioned in the introduction (Section 6.3.2.1), the term for self-defence found in many civil law countries combines two concepts, one entailing distress, emergency, or danger, and the other meaning to protect or defend. This is the case in Danish law, where ‘nød’ refers to the former and ‘værge’ the latter. It is therefore more appropriately referred to as necessary or legitimate defence, rather than self-defence. In order to be lawful self-defence, the initial attack must entail an unlawful use of force, and the response must be necessary and proportionate.303 According to the Danish Military Manual, the right of self-defence may not be used as a justification for failure to comply with for instance hold fire orders or for carrying certain weapons.304
6.3.2.3.2 Dutch Law
- 1.A person who commits an offense where this is necessary in defense of his person or the person of another, his or another person’s integrity or property, against immediate, unlawful attack is not criminally liable [justification].
- 2.A person exceeding the limits of necessary defense, where such excess has been the direct result of a strong emotion brought about by the attack, is not criminally liable [excuse].305
Thus, in Dutch law, self-defence functions as a ground for excluding criminal responsibility, and will operate as a justification, unless the force is excessive, in which case it may be an excuse. The term used for self-defence in Dutch law is “noodweer”, which is another example of the civil law tendency to combine distress, emergency, or danger, and protect or defend (‘nood’ and ‘weer’) into a concept of necessary or legitimate defence. Like the legislation in other civil law counties, force may be used in self-defence of oneself, another and objects, and there is a requirement that the initial attack is unlawful. Although there is no reference to a duty to retreat in the legislation, this has been applied in case law.306
6.3.2.3.3 French Law
In French criminal law, self-defence is dealt with as ‘legitimate defence’, which operates as a justification.307 Article 122–5 of the French Penal Code permits the defence of oneself or another where such force is necessary and proportionate: “A person is not criminally liable if, confronted with an unjustified attack upon himself or upon another, he performs at that moment an action compelled by the necessity of self-defence or the defence of another person, except where the means of defence used are not proportionate to the seriousness of the attack”.308 As the reference to “at that moment” suggests, the response must be taken immediately.309
Protection of property is dealt with in a separate paragraph where it is made clear that wilful murder never will be necessary or proportionate use of force to defend property: “A person is not criminally liable if, to interrupt the commission of a felony or a misdemeanour against property, he performs an act of defence other than wilful murder, where the act is strictly necessary for the intended objective the means used are proportionate to the gravity of the offence”.310
The French self-defence provision also makes it clear that the initial attack must be unlawful, or as it is phrased, unjustified. According to Elliot, if defendants misunderstand the situation and mistakenly believe they are about to be attacked, they may be able to rely on the defence if the mistake was reasonable.311 Finally, self-defence may be relied upon in response to both actual and imminent attacks.312
Due to challenges arising from French military forces having to rely on self-defence during military operations, a new legal basis was introduced in 2005 for the use of force to accomplish the mission, when doing so is in accordance with international law.313 The provision applies to operations outside of French territory and territorial waters. Although some consider it to be an exception to self-defence,314 it should principally be viewed as an alternative legal basis for the use of force, and the framework for rules of engagement implementation (see also Section 5.1.2 on lawful acts of war).
As a result of increased terrorist attacks, a recent law aligned self-defence standards of national and local police and military units deployed on French territory to that of the French gendarmerie.315 Security forces may now rely on self-defence to use force in a broader set of circumstances, for example to prevent a murder where they have a real reason to believe that this is about to happen.
6.3.2.3.4 German Law
In German law, self-defence is a justification that may be considered in relation to a criminal case, as opposed to an independent right.316 According to the German Criminal Code Section 32, a person who “commits an act in self-defence does not act unlawfully”. Furthermore, “[s]elf-defence means any defensive action that is necessary to avert an imminent unlawful attack on oneself or another”.317 Like many other European self-defence rules, German self-defence includes the defence of others and is not limited to the use of force (‘any defensive action’). This is reflected in the terminology: rather than being termed self-defence or defence of self, it is called ‘notwehr’.318 This term combines two concepts, one entailing distress, emergency, or danger (‘not’), and the other (‘wehr’) meaning to protect or defend. A better translation of this concept is therefore necessary or legitimate defence.319
The German self-defence rule has been described as traditionally being “‘strong’ and aggressive in Germany”,320 in that it does not require retreat except where the threat originates from, for instance, a child or insane person, and permits the use of means that “averts the attack reliably and permanently”.321 Furthermore, according to Section 33, excessive self-defence may be excused, provided the use of force in self-defence is still necessary: “a person who exceeds the limits of self-defence out of confusion, fear or terror shall not be held criminally liable”.322
There is no mention of a proportionality requirement in the German self-defence provision; however, this does not mean that the right to defend is unlimited.323 The requirement of necessity is interpreted to require that the force used is proportional. According to Lencker and Perron, courts have imposed limitations for reasons of “social ethics”.324 One of these is the doctrine of ‘abuse of rights’: self-defence must not be exercised in an abusive way.325
6.3.2.3.5 Norwegian Law
An act which would otherwise be punishable, is lawful when it
- a.is committed to avert an unlawful attack,
- b.does not exceed what is necessary, and
- c.does not clearly go beyond what is justifiable, taking into account the dangerousness of the attack, the type of interest the attack violates, and the culpability of the assailant.327
The provision requires that the initial threat be unlawful,328 which has been interpreted to mean “not within the ordinary freedom of action”,329 and that the response be limited to what is necessary and justifiable. The initial attack may have been directed at a person or object, and the defensive measure can taken both by the attacked person and a third party. This means that Norwegian soldiers may use force in self-defence to protect property, although the use of lethal force is only likely to be considered necessary and justifiable if the damage to the property will also entail a serious risk of harm to persons. This may, for instance, be the case with mission-essential property. Furthermore, the defensive measure may be taken both by the attacked person and a third party, and may therefore be used as the basis for defending both the unit, other coalition forces and civilians.
There is no requirement that the attack has started or even that it is imminent. However, in such cases, it is less likely that the defensive use of otherwise unlawful measures meet the necessity requirement.330 The issues of retreat and provocation are not explicitly dealt with, but are nevertheless considered relevant for the assessment of whether the force used was necessary and justifiable.331 If the defensive response is excessive, thereby failing the self-defence requirements, it may nonetheless result in a reduction of penalty, or in certain circumstances, the act being excused.332 Finally, it is also required that the defensive measure be directed at the source of the threat, thereby excluding the possibility relying on self-defence to justify harm to innocent bystanders.333
The Norwegian Manual on the Law of Armed Conflict makes it clear that while the defence of self may not be limited, defence of others and objects may be subjected to limitations, for instance through roe.334
6.3.2.3.6 UK Law335
In the United Kingdom, self-defence, or private defence as it is also referred to, is a common law defence,336 but elements of the defence have been clarified in the 2008 Criminal Justice and Immigration Act. Section 76 sets out the requirements for when a person may rely on self-defence, in particular as to whether the degree of force used was reasonable.337 Defence of property is not considered part of self-defence, but the use of force against another person to protect property may be justified as prevention of crime.338 Section 76 applies to: self-defence, including the defence of others; defence of property; and the use of force in prevention of crime or making arrest.339
(3) The question whether the degree of force used by D was reasonable in the circumstances is to be decided by reference to the circumstances as D believed them to be (…)
(4) If D claims to have held a particular belief as regards the existence of any circumstances –
(a) the reasonableness or otherwise of that belief is relevant to the question whether D genuinely held it; but
(b) if it is determined that D did genuinely hold it, D is entitled to rely on it for the purposes of subsection (3), whether or not –
(i) it was mistaken, or
(ii) (if it was mistaken) the mistake was a reasonable one to have made.
(5) But subsection (4)(b) does not enable D to rely on any mistaken belief attributable to intoxication that was voluntarily induced.
(5A) In a householder case, the degree of force used by D is not to be regarded as having been reasonable in the circumstances as D believed them to be if it was grossly disproportionate in those circumstances.
(6) In a case other than a householder case, the degree of force used by D is not to be regarded as having been reasonable in the circumstances as D believed them to be if it was disproportionate in those circumstances.
(6A) In deciding the question mentioned in subsection (3), a possibility that D could have retreated is to be considered (so far as relevant) as a factor to be taken into account, rather than as giving rise to a duty to retreat.
(7) In deciding the question mentioned in subsection (3) the following considerations are to be taken into account (so far as relevant in the circumstances of the case) –
(a) that a person acting for a legitimate purpose may not be able to weigh to a nicety the exact measure of any necessary action; and
(b) that evidence of a person’s having only done what the person honestly and instinctively thought was necessary for a legitimate purpose constitutes strong evidence that only reasonable action was taken by that person for that purpose.341
The initial test of necessity is subjective, primarily requiring that the belief be genuinely held.342 It is emphasised that a person who honestly believes that the defensive force is necessary should be considered to have acted reasonably, even if this is based on a reasonable mistake. Defensive force may be used in response to both actual and imminent attacks, but the imminence requirement is strictly construed.343 The degree of force used will not be considered reasonable if it is disproportionate. This test is in other words more objective, although reasonableness must be assessed in light of the defendant’s perception of the circumstances. Furthermore, it is recognised that it may be difficult for the defendant to “weigh to a nicety” the amount of force used in order to ensure it is proportionate and hence reasonable.344 If the defendant could have retreated, this will affect the assessment of whether the degree of force used was reasonable.345 The defendant will generally not be able to rely on self-defence if the attack was provoked.346
Common law self-defence permits the use of force against an unjustified attack, which includes unlawful attacks.347 This rule has been supplemented by Section 3(1) of the Criminal Law Act of 1967, which permits the use of force specifically in the prevention of crime. The 1967 Act modifies, rather than replaces, the common-law rule,348 and, as explained above, the determination of reasonableness under both legal bases is made by reference to the same test under Section 76.349 Because most instances of force being used in self-defence involve prevention of crime, they will fall under the 1967 Act rather than common law self-defence. However, the common law defence will also be applicable where force is used against an unjustified attack that is not criminal under British law. For example, the act may be unjustified because it is unlawful in international law.350 Furthermore, common law self-defence will be available as a defence even if the attacker for instance is a minor and therefore not criminally liable.351 In the proposed Criminal Law Bill, a distinction is made between self-defence, which is the protection against an unlawful attack; the termination of commission of a crime; and termination of interference with property.352
Although British courts have been presented with self-defence claims from military forces accused of unlawful use of force, few if none have been accepted.353 One of the few cases where it was accepted was in the 1975 case of Attorney-General for Northern Ireland’s Reference;354 however, because the UK did not consider the situation in Northern Ireland to be a niac, the case is less relevant here.
6.3.2.3.7 U.S. Uniform Code of Military Justice and Rules for Courts-Martial
(1) Homicide or assault cases involving deadly force. It is a defense to a homicide, assault involving deadly force, or battery involving deadly force that the accused:
A. Apprehended, on reasonable grounds, that death or grievous bodily harm was about to be inflicted wrongfully on the accused; and
B. Believed that the force the accused used was necessary for protection against death or grievous bodily harm.
(2) Certain aggravated assault cases. It is a defense to assault with a dangerous weapon or means likely to produce death or grievous bodily harm that the accused:
A. A. Apprehended, on reasonable grounds, that bodily harm was about to be inflicted wrongfully on the accused; and
B. In order to deter the assailant, offered but did not actually apply or attempt to apply such means or force as would be likely to cause death or grievous bodily harm.
(3) Other assaults. It is a defense to any assault punishable under Article 90, 91, or 128 and not listed in subsections (e)(1) or (2) of this rule that the accused:
A. Apprehended, upon reasonable grounds, that bodily harm was about to be inflicted wrongfully on the accused; and
B. Believed that the force that accused used was necessary for protection against bodily harm, provided that the force used by the accused was less than force reasonably likely to produce death or grievous bodily harm.
(4) Loss of right to self-defense. The right to self-defense is lost and the defenses described in subsections (e)(1), (2), and (3) of this rule shall not apply if the accused was an aggressor, engaged in mutual combat, or provoked the attack which gave rise to the apprehension, unless the accused had withdrawn in good faith after the aggression, combat, or provocation and before the offense alleged occurred.
(5) Defense of another. The principles of self-defense under subsection (e)(1) through (4) of this rule apply to defense of another. It is a defense to homicide, attempted homicide, assault with intent to kill, or any assault under Article 90, 91, or 128 that the accused acted in defense of another, provided that the accused may not use more force than the person defended was lawfully entitled to use under the circumstances.360
The first requirement in Sections 1(A), 2(A) and 3(A) is objective, requiring the apprehension of harm; hence, the need for using force must be reasonable. According to the commentary provided in the ucmj to Section 1, “such matters as the relative height, weight, and general build of the accused and the alleged victim, and the possibility of safe retreat are ordinarily among the circumstances which should be considered in determining the reasonableness of the apprehension of death or grievous bodily harm”.361 The second element is subjective, and concerns the degree and amount of force used (proportionality); the accused must have actually believed that the degree and amount of force used was necessary.362 In the case of homicide, it will not matter if the force used is excessive as long as the belief that the degree or amount of force used was necessary is actually held.363
The ability to rely on self-defence is extensively set out in the Military Judges’ Benchbook. The Benchbook is a non-binding guide that serves as a restatement of the law for use by military judges in instructing members of courts-martial.364 Only the most relevant aspects will be commented on here. First, the threat must be immediate, or “about to be inflicted”, which is interpreted to mean immediate.365 Furthermore, as in most other formulations of personal self-defence, there is a requirement that the initial attack be wrongfully inflicted (see Sections 1(A), 2(A) and 3(A) above). Interestingly, this requirement is not mentioned in the Military Judges Benchbook. It is not clear whether this is because the requirement of unlawful attack is not applied, or more likely, whether it is applied at a different stage in the process, such as the decision to prosecute and on what grounds, thereby preventing cases of defence against an unlawful attack from going to trial. The rcm also makes it clear that self-defence may not be claimed if the assault is intentionally provoked (Section 4 above).366 With regards to retreat, there is no requirement of retreat from a place that the accused has a right to be, but it may be a factor in deciding whether or not the accused acted in self-defence.367
The application of self-defence by military forces is also dealt with in the U.S. sroe. Although it is emphasised that all forces retain the right of self-defence, it is also made clear that “[w]hen individuals are assigned and acting as part of a unit, individual self-defense should be considered a subset of unit self-defense”.368 The sroe has been criticised for including a very expansive definition of imminence, declaring that “imminent does not necessarily mean immediate or instantaneous”.369 It also appears to be a departure from the requirement set out in the U.S. rcm and the relevant Military Judges’ Benchbook guidance, where, as mentioned above, the requirement is that the threat is “about to” occur, meaning it is immediate. The reason for the departure is likely due to the reliance on jus ad bellum as the legal basis for the use of force in self-defence during armed conflict.370 Not surprisingly, however, in trials arising from military forces participating in an armed conflict where self-defence has been accepted, the courts apply the provision in the ucmj.371 According to Gaston, “[a]s a result, although the U.S. in many ways has the greatest guidance on his issue, (…) substantial ambiguity remains over how exactly standards will be applies to soldiers relying on self-defense in different armed conflict situations”.372
6.4 Conclusion
One of the few commentators on the application of self-defence by State officials, including military forces, Gloria Gaggioli, recently raised concerns about “the challenges pertaining to the multifaceted concept of self-defence in military operations (jus ad bellum self-defence, ‘unit self-defence’, personal self-defence, defence of others) and overlapping legal regimes (notably domestic/operational law, international humanitarian law, human rights law, jus ad bellum)”.373 Contributing towards much needed clarity on the applicable law and how it applies in the unique context of military operations involving participation in an armed conflict is one of the aims of this book. This chapter has sought to answer the first question, namely what does the reference to inherent right of self-defence in roe actually refer to?
First, it is argued that personal self-defence and the use of defensive force by military forces involved in an armed conflict must be distinguished from the concept of State self-defence. Except in the case of a third State or non-State party becoming involved in an ongoing armed conflict, State self-defence will not provide authorities to use force. Instead, the only relevant legal self-defence concept is personal self-defence.374
A general concept of personal self-defence, beyond the narrow concept found in icl, is implicitly recognised in international law such as ihrl. However, neither a human right to self-defence nor a customary rule of personal self-defence could be found to exist. Furthermore, while good arguments can be made for the existence of a general principle of international law, it is unclear what the practical implications are of such an assertion. Except in the rare cases of military forces being tried before an international criminal court or tribunal, the use of force by military forces is usually assessed by a domestic court. Such courts are most likely to apply the concept of self-defence found within their domestic legislation. Personal self-defence is, after all, a right originating in the domestic context, from which it has expanded to international law, not vice versa. Military forces should therefore not interpret the reference to ‘inherent right of self-defence’ to mean that there is a legal concept of self-defence beyond the criminal law concept. The historic and universal nature of the right does, however, entail that same criteria are applied in all jurisdictions, albeit in slightly different ways. These are: unlawfulness, necessity/imminence, and proportionality; that the assessment of the situation is perceived as reasonable; and that force was used with an intention to repel the attack.375
The second half of the question raised above will be examined in the Part 3 of this book, in Chapter 8: how does self-defence apply during armed conflict operations? First, the scope of relying on the legal concept of personal self-defence will be examined in detail. Because this is considerably more narrow than the references to self-defence by military forces would suggest, the existence of operational concepts of self-defence will also be examined. Whereas the legal concept of self-defence provide an exception from the prohibition on arbitrary deprivation of life, such operational self-defence concepts provide use of force authorities as exceptions to the general rule that all use of force must be authorised by roe. To the extent the use of force not authorised by roe does not meet the requirement of self-defence, it must be based on a different legal authority, which during armed conflict operations is most likely to be loac.
Pope Gregory IX, Liber quintus (Decretal V), Titulus xxxix, Cap. iii (available at
Erica L. Gaston, ‘Reconceptualizing Individual or Unit Self-Defense as a Combatant Privilege’, 8(2) Harvard National Security Journal 283 (2017), p. 295.
On the right to life, see Section 4.2.
See Section 4.1.
Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of victims of International Armed Conflicts (Protocol I) (1977), printed in Schindler, Dietrich and Jiri Toman, The Laws of Armed Conflicts, Martinus Nijhoff Publisher, 1988, pp. 711ff, Article 49(1).
See also Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) p. 288, and Erica L. Gaston, When Looks Could Kill: Emerging State Practice on Self-Defense and Hostile Intent (Global Public Policy Institute, 2017,
Jon Boone, ‘Nato air attack on Pakistani troops was self-defence, says senior western official’, The Guardian (27 November 2011,
Shashank Bengali, W.J. Hennigan, and Ali M. Latifi, ‘U.S. changes its account of hospital bombing, says Afghans requested attack’, Los Angeles Times (05 October 2015,
Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, I.C.J. Reports [1996] 226, para. 96.
Jan Arnold Hessbruegge, Human Rights and Personal Self-Defense in International Law, Oxford University Press, New York, 2017, p. 232.
J.F.R. Boddens Hosang, ‘Self-Defence in Military Operations: The Interaction between the Legal Bases for Military Self-Defence and Rules of Engagement’, 47 Military Law and Law of War Review 25 (2008), pp. 75–77. See also Ian Henderson and Bryan Cavanagh, ‘Military members claiming self-defence during armed conflict – Often misguided and unhelpful’ [hereinafter: ‘Claiming self-defence on the battlefield’], in Jadranka Petrovic (ed.), Accountability for Violations of International Humanitarian Law – Essays in honour of Tom McCormack (Routledge, London/New York, 2016) p. 75.
See also Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) pp. 288–289 and 295. According to Dinstein, “[t]he legal notion of [State] self-defence has its roots in interpersonal relations, and has been sanctified in domestic legal systems since time immemorial.” Yoram Dinstein, War, Aggression and Self-Defence (Cambridge University Press, Cambridge, 2011) p. 188.
See Section 6.2.2 below.
nato, Military Decision on MC 362/1 – nato Rules of Engagement [hereinafter MC 362/1], 30 June 2003, p. 4. The MC 362/1 is nato unclassified, however, permission to use parts of the document for the purposes of this research is granted by the nato Military Commission in document imstam(O&P)-0006-2018 (copy on file with the author). In particular, it is explained that all use of force in self-defence, without specifying the type of self-defence, must comply with the requirement that “the need to defend is manifest, instant and overwhelming”. See also nato, STANAG 2597: Training in Rules of Engagement, ATrainP-4 [hereinafter: STANAG 2597], 4 May 2015 (available at
See e.g. Hans F.R. Boddens Hosang, ‘Force Protection, Unit Self-Defence, and Personal Self-Defence: Their Relationship to Rules of Engagement’, Chapter 24 in Terry D. Gill and Dieter Fleck (eds.), The Handbook of the International Law of Military Operations (Oxford University Press, Oxford, 2015) pp. 483–484, §24.08, paragraphs 4–7 and §24.09 with commentaries; and the U.S. position as discussed e.g. in Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) pp. 296–297.
State self-defence has for centuries been the subject of considerable debate and study, and numerous important works deal with the topic in extensive detail. For a selection of writings, see Derek W. Bowett, Self-Defence in International Law (Oxford University Press, Oxford, 1958); Ian Brownlie, International law and the use of force by States (Oxford University Press, Suffolk, 1963 (1991 reprint)), especially Chapter xiii; Dinstein, War, Aggression and Self-Defence (n 12); Arthur Eyffinger, Sam Muller; and Alan Stephens (eds.), Self-defence as a Fundamental Principle (Hague Colloquium in Fundamental Principles of Law, Hague Academic Press, 2009); Terry D. Gill, ‘Legal basis of the right of self-defence under the UN Charter and under customary international law’, Chapter 8 in Terry D. Gill and Dieter Fleck (eds.), The Handbook of the International Law of Military Operations (Oxford University Press, Oxford, 2012 reprint); Terry Gill, Carl Marchand, Hans Boddens Hosang, and Paul Ducheine, ‘General Report’, in Stanislav Horvat and Marco Benatar (eds.), Legal Interoperability and Ensuring Observance of the Law Applicable in Multinational Deployments (Proceedings of the 19th International Congress, Quebec, xix Recueil of the International Society of Military Law and Law of War, Brussels, 2013) pp. 126–140; Christine Gray, International law and the Use of Force (Oxford University Press, NY, 2008) Chapters 4–6; Institut droit international, ‘Present Problems of the Use of Force in International Law: Sub-group on Self-defence’, Annuaire de l’Institut de droit international – Session de Santiago du Chili, Volume 72, 2007; Albrecht Randelzhofer and Georg Nolte, ‘Article 51’, in Bruno Simma et al. (eds.), The Charter of the United Nations – A Commentary (Oxford University Press, Oxford, 2012) Volume II, pp. 1397–1428; Tom Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (Cambridge University Press, Cambridge, 2010); C.H.M. Waldock, ‘The Regulation of the Use of Force by Individual States in International Law’, 81 Recueil des cours de I’Academie de droit international de La Haye, 1952; and Elizabeth Wilmshurst, ‘The Chatham House principles of international law on the use of force in self-defence’, 55(4) International and Comparative Law Quarterly 963 (2006).
In order to distinguish the interpersonal form of self-defence from the State form of self-defence (regulated by the jus as bellum), the phrase personal self-defence will be used to describe the use of force by a person in protection of self, others and, where applicable, property.
George P. Fletcher and Jens David Ohlin, Defending Humanity: When force is justified and why (Oxford University Press, Oxford, 2008) p. 26. See pp. 26–29 for a brief overview of the historic origins of self-defence, and for instance Christopher D. Amore, ‘Rules of Engagement: Balancing the (Inherent) Right and Obligation of Self-Defense with the Prevention of Civilian Casualties’, 1 National Security Law Journal 39 (spring 2013), pp. 44–46.
Gary P. Corn, ‘Should the Best Offense Ever be a Good Defense? The Public Authority to Use Force in Military Operations: Recalibrating the Use of Force rules in the Standing Rules of Engagement’, 49 Vanderbilt Journal of Transnational Law 1 (2016), p. 3.
See further Section 2.2.1.4. However, as will be discussed in Section 8.2.10, States may agree to roe imposing limitations, in particular on the use of force in defence of others or property.
See further Section 3.5.
icrc, Interpretive Guidance on the Notion of Direct Participation in Hostilities under International Humanitarian Law [hereinafter icrc Interpretive Guidance] (May 2009, prepared by Nils Melzer, available at
Gill et al. ‘General Report’ (n 16) p. 123.
See un ilc, ‘State responsibility’, in Analytical Guide to the Work of the International Law Commission (available at
un ilc, ‘Report of the International Law Commission on the work of its thirty-second session (5 May-25 July 1980)’, Document A/35/10, Yearbook of the International Law Commission, 1980, Vol. II, Part two, p. 26, at p. 52. The 1980 report represents the main discussion on circumstances precluding wrongfulness, namely state of necessity and self-defense, in preparation for the Articles on State Responsibility. The ilc report was based on the preparations of Special Rapporteur Roberto Ago: Roberto Ago, ‘Addendum to the Eight Report on State Responsibility’ (1980), Document A/CN.4/318/Add.5–7, Yearbook of the International Law Commission 1980, Vol. II, Part one, p. 52.
Fiona Leverick, Killing in Self-Defence (Oxford Monographs on Criminal Law and Justice, Oxford University Press, Oxford, 2006) p. 1.
Hans Boddens Hosang, Rules of Engagement (PhD thesis, University of Amsterdam 2017, available at
Bowett, Self-Defence in International Law (n 16) p. 8. On the nature of self-defence as a right, see further Section 6.3.2.1.2.
un ilc, ‘Draft Articles on State Responsibility with Commentaries’, Yearbook of the International Law Commission, 2001, Vol. II, Part Two, p. 30, p. 72.
See e.g. Seumas Miller, Shooting to Kill: The Ethics of Police and Military Use of Lethal Force (Oxford University Press, 2016); Michael Walzer, Just and unjust wars (Basic Books, New York, 5th ed, 2015); David Rodin, War and Self-Defence (Oxford University Press, 2002); Fletcher and Ohlin, Defending Humanity (n 18) p. 26; Leverick, Killing in Self-Defence (n 26) Chapter 3 (pp. 43–68).
General treaty for the Renunciation of War as an Instrument of National Policy, 94 League of Nations Treaty Series 57 (1928). See Dinstein, War, Aggression and Self-Defence (n 12) p. 85; J.L. Brierly, The Law of Nations: An Introduction to the International Law of Peace (Sir Humphrey Waldock (ed.), Oxford, Oxford University Press, 1963) pp. 403–410, and Brownlie, International Law and the Use of Force by States (n 16) pp. 74–92.
Covenant of the League of Nations, 28 April 1919 (available at
For instance the Geneva Protocol for the Pacific Settlement of International Disputes, adopted by the Fifth Assembly of the League of Nations on 2 October 1924 (but never entered into force), available at
Dinstein, War, Aggression and Self-Defence (n 12) p. 85. According to Ian Brownlie, it was ratified or adhered to by sixty-three States which mean that it was of “almost universal obligation since only four States in international society as it existed before the Second World War were not bound by its provisions”. Brownlie, International Law and the Use of Force by States (n 16) p. 75.
Brierly, The Law of Nations (n 31) p. 409.
Kellogg-Briand Pact (n 31) p. 63.
Statement by the American Government made before the conclusion of the Pact, cited in: Ago, ‘Addendum to the Eight Report on State Responsibility’ (n 25) p. 59 and un ilc, ‘Report of the International Law Commission on the work of its thirty-second session’ (n 25) p. 56, footnote 195. The American Secretary of State insisted that it was important to keep the treaty simple, and that inclusion of an exception for self-defence was superfluous. Instead, many States referred to the American Statement when signing and acceding to the Pact.
Kellogg-Briand Pact (n 31) pp. 59–61.
Dinstein, War, Aggression and Self-Defence (n 12) p. 86.
Charter of the United Nations (UN Charter), 24 October 1945, 1 unts xvi.
ibid, Article 2(4).
ibid, Article 39.
ibid, Article 42.
ibid, Article 51.
Terry D. Gill, ‘The Temporal Dimension of Self-Defence: Anticipation, Pre-emption, Prevention and Immediacy’, in Michael N. Schmitt and Jelena Pejic (eds.), International Law and Armed Conflict: Exploring the Faultlines: Essays in Honour of Yoram Dinstein (brill, 2007) p. 116. See also Bowett, Self-Defence in International Law (n 16) pp. 182–183.
Nigel D. White, ‘Defending Humanity: When Force is Justified and Why by George P. Fletcher and Jens David Ohlin (book review)’, 10 Melbourne Journal of International Law 379 (2009), p. 381.
On State self-defence and natural law, see for instance John J. Merriam, ‘Natural Law and Self-Defense’, 206 Military Law Review 43 (2010), pp. 43–87 and Jens David Ohlin, ‘The Doctrine of Legitimate Defense’, 91 International Law Studies 119 (2015).
Hugo Grotius De jure belli ac pacis libri tres (On the Law on War and Peace)(first published 1625, translated by Francis W. Kelsey, The Classics of International Law, No. 3 vol. II, Carnegie Endowment for International Peace, Oxford/ Clarendon, 1925) Book II, Chapter i, Section iii, p. 172. See also ibid, Section xvi, p. 184; Balthazar Ayala, De Jure et Officiis Bellicis et Disciplina Militari (On the Law of War And on the Duties Connected with War And on Military Discipline) (first published 1582, translated by John Pawley Bate, The Classics of International Law, No.2 Vol II, Carnegie Institution of Washington, Washington D.C., 1912) p. 11, Book I, Chapter II, §11; Alberico Gentili, De Jure Belli Libri Tres (The Three Books on the Law of War)(first published 1612, translated by John C. Rolfe, The Classics of International Law No 16 Vol II, Oxford University Press, Oxford, 1933) Book I, Chapter xiii, pp. 58–59 [94]; Fransisco Suarez, De Legibus, Ac Deo Legislatore (A Treatise on Laws and God the Lawgiver)(first published 1612, translated by Gwladys L. Williams and Ammi Brown, The Classics of International Law No. 20 Vol 2, Oxford University Press, Oxford, 1944) Book II, Chapter xvii, §6, p 329 [182]; Emer de Vattel, Le droit des gens; ou, Principes de la loi naturelle appliqués à la conduite et aux affaires des nations et des souverains (The Law of Nations or the Principles of Natural Law Applied to the Conduct and to the Affairs of Nations and of Sovereigns)(first published 1758, translated by Charles G. Fenwick, The Classics of International Law, No. 4 vol. iii. Carnegie Institution of Washington, Washington D.C., 1916) Book iii, Chapter iii, pp.243–244, §§ 26–27, and p. 246, § 35, and Book iii Chapter I, p. 233, § 3; and Christian Wolff, Jus Gentium Methodo Scientifica Pertractatum (The Law of Nations Treated According to a Scientific Method) (first published 1764, translation by Joseph H. Drake, The Classics of International Law No 13 Vol 2, Oxford University Press, Oxford, 1934) Book I, Chapter II, pp. 129–130, §§252–253.
According to Jennings, self-defence “was rescued from the Naturalist notions of an absolute primordial right of self-preservation, which still vitiated the doctrine of the writers, and was subjected to the limiting condition of necessity”. R.Y. Jennings, ‘The Caroline and McLeod Cases’, 32 American Journal of International Law 82 (1938), p. 92. For examples of early writings on state self-defence from a naturalist perspective, see note 48 above.
For further information on the facts, see ibid, especially pp. 82–84.
In regard to this distinction between individual responsibility and state responsibility, see Chapter 4, note 132 and accompanying text.
Caroline Incident Letters, published British and Foreign State Papers, 1841–1842 (London, Ridgeway, 1858), vol. 30, p. 193, available at
Caroline Incident Letters, published in British and Foreign State Papers, 1840–1841 (London, Ridgeway, 1857, vol. 29, p. 1126,
“It was in the Carline case that self-defence was changed from a political excuse to a legal doctrine”. Jennings, ‘The Caroline and McLeod Cases’ (n 49) p. 82.
League of Nations, Responsibility of States for Damage caused in their Territory to the Person or Property of Foreigners, Conference for the Codification of International Law, Bases of Discussion for the Conference drawn up by the Preparatory Committee, vol. Ill, League of Nations Doc C. 75. M. 69.1929 V, p. 125.
See e.g., the responses by Belgium: “In the case of legtimate self-defence against an aggressor State, for damage caused to the nationals of that State or damage caused to nationals of third States necessitated by the state of war” (ibid, p. 125); and Denmark: “Only in exceptional cases when, for instance, from a vessel outside territorial waters acts are committed which constitute an unlawful attack and a danger to the security of the coastal State, would it be possible, in the relations between a State and private individuals, to adopt the particular plea of self-defence” (ibid, p. 126).
“[A] total prohibition without ‘loopholes’ on recourse to war would not affect the right to resort to war in cases where the conditions of a situation of self-defence were fulfilled”. un ilc, ‘Report of the International Law Commission on the work of its thirty-second session’ (n 25) p. 56, referencing the reply of the Italian Government (League of Nations, Official Journal, 12th year, No. 8 (August 1931), p. 1602; the statement by the representative of Germany in League of Nations, Official Journal, Special Supplement No. 94 (1931), p. 41; and the report prepared in the close of the proceedings of the First Committee and submitted to the twelfth session of the Assembly, in League of Nations, Official Journal, Special Supplement No. 93 (1931), pp. 221ff.
Nuremberg Tribunal Judgement of 1 October 1946, reproduced in Trial of the Major War Criminals before the International Military Tribunal, Nuremberg, 14 November 1945–1 October 1946 (Nuremberg, 1947), vol. 1 (
ibid, p. 207.
ibid, p. 209.
ibid, pp. 207–208.
United States v. Von Weizsaecker et al, (‘Ministries Case’) Trials of War Criminals before the International Military Tribunal Under Control Council Law No. 10, Nuremberg, October 1946-April 1947 (Nuremberg, 1947), vol. xiv (
International Military Tribunal for the Far East, Judgement of 12 November 1948, in John Pritchard and Sonia M. Zaide (eds.), The Tokyo War Crimes Trial, Garland (London/New York, 1981) Vol. 22, pp. 421–422 (charges), and pp. 581 and 762–770 (regarding the claim of and non-application of self-defence).
ibid, p. 494.
ibid, pp. 443–444 and 585–586. For more information on jus ad bellum self-defence cases arising out of the Second World War, see Timothy L.H. McCormack, ‘Self-Defence in International Criminal Law’, in Hirad Abtahi and Gideon Boas (eds.), The Dynamics of International Criminal Justice: Essays in the honour of Sir Richard May (brill, 2005) pp. 245–251.
See Ago, ‘Addendum to the Eight Report on State Responsibility’ (n 25) pp. 62–63.
In the response to question XI (a) of the questionnaire prepared for the Hague Conference of 1930 on the Responsibility of States for Damage Caused to the Person or Property of Foreigners, Switzerland emphasises that: “Although conditions of legitimate defence must exist directly the State becomes the victim of an “unjust aggression contrary to law”, it has not yet been possible internationally to obtain a satisfactory definition of aggression”. League of Nations, Responsibility of States for Damage caused in their Territory to the Person or Property of Foreigners (n 55) p. 127.
See e.g. Gill, ‘The Temporal Dimension of Self-Defence’ (n 45) p. 117. See also Case Concerning Oil Platforms (Iran v United States), I.C.J. Reports [2003] 161, Judgement, para. 76–77, and Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda), Judgment, I.C.J. Rep 2005, p. 168, para. 147.
Case Concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America), Merits, Judgement, I.C.J. Reports [1986] 14, para. 176.
See e.g. an overview over topics that have been subject to academic debate in Gray, International Law and the Use of Force (n 16) pp. 117–119.
For a brief overview of this debate, see Randelzhofer and Nolte, ‘Article 51’ (n 16), pp. 1403–1406 and Brownlie, International Law and the Use of Force by States (n 16) pp. 272–275. See also icj Nicaragua Case (n 69) Merits, para. 211, reaffirmed in the icj Oil Platforms Case (n 68) Judgement para 51, where the customary rule of self-defence is treated as being the same as Article 51, with the exception of the requirement to report to the Security Council (icj Nicaragua Case, Merits, para 200).
See note 74 below and accompanying text.
Gill, ‘Legal basis of the right of self-defence under the UN Charter and under customary international law’ (n 16) p. 215.
Ago, ‘Addendum to the Eight Report on State Responsibility’ (n 25) p. 15 and pp. 64–65; Dinstein, War, Aggression and Self-Defence (n 12) pp. 193ff and 231; Gray, International Law and the Use of Force (n 16) pp. 128–148; Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) in particular Chapter 3; Randelzhofer and Nolte, ‘Article 51’ (n 16) pp. 1406ff; Michael N. Schmitt, ‘Responding to Transnational Terrorism under the Jus Ad Bellum: A Normative Framework’, 56 Naval Law Review 1 (2008), pp 13–15; Brownlie, International Law and the Use of Force by States (n 16) pp. 278–279. Some, however, argue that force may also be used in response to acts other than armed attack under a parallel customary rule of self-defence, see e.g., Bowett, Self-Defence in International Law (n 16) pp. 192–193; and Waldock, ‘The Regulation of the Use of Force’ (n 16) pp. 496–499.
icj Armed Activities Case (n 68) para. 148.
See icj Nicaragua Case (n 69) Merits, para. 195 and icj Oil Platforms Case (n 68) para 51. See also Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 139–15, and Dinstein, War, Aggression and Self-Defence (n 12) pp. 207–212. This distinction between armed attack and lesser forms of use of force entails that there are instances that violate Article 2(4) of the UN Charter that may not be responded to with armed self-defence.
For instance, the intervention in Afghanistan in 2001 (Operation Enduring Freedom) was categorised by the U.S. and the UK as the exercise of the right of anticipatory self-defence. See unsc, ‘Letter dated 2001/10/07 from the Permanent Representative of the United States of America to the United Nations addressed to the President of the Security Council’ [7 October 2001] U.N. Doc. S/2001/946: “United States armed forces have initiated actions designed to prevent and deter further attacks on the United States”, and unsc, ‘Letter dated 7 October 2001 from the Chargé d’affaires a.i. of the Permanent Mission of the United Kingdom of Great Britain and Northern Ireland to the United Nations addressed to the President of the Security Council’ [7 October 2001] UN Doc S/2001/947. More controversially, one of the legal bases offered by the U.S. for invading Iraq in 2003 (Operation Iraqi Freedom) was a pre-emptive form of self-defence, also referred to as the ‘Bush-doctrine’. See summary of the debate in Gray, International Law and the Use of Force (n 16) pp. 181–184. There are extensive writings on these issues. See e.g.: Dinstein, War, Aggression and Self-Defence (n 12) pp. 194–200; Christopher Greenwood, ‘International Law and the Pre-emptive Use of Force: Afghanistan, Al-Qaida, and Iraq’, 4 San Diego International Law Journal 7 (2003); Gill, ‘The Temporal Dimension of Self-Defence’ (n 45) pp. 113–155; Harold Hongju Koh, ‘On American Exceptionalism’, 55 Stanford Law Review 1479 (2002–2003); Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 250–342; and Schmitt, ‘Responding to Transnational Terrorism’ (n 74) pp. 16–20 and 35–40.
Dinstein, War, Aggression and Self-Defence (n 12) p. 206.
ibid.
For a detailed examination of the temporal requirement of the existence of an armed attack, including the issue of imminence, see Gill, ‘The Temporal Dimension of Self-Defence’ (n 45) pp. 128–150.
Letter from Mr. Webster to Mr. Fox, Caroline Incident Letters (n 53) p. 1138.
Michael N. Schmitt, ‘Targeted Killings and International Law: Law Enforcement, Self-defense and Armed Conflict’, Chapter XX in Roberta Arnold and Noëlle Quénivet, International Humanitarian Law and Human Rights Law – Towards a New Merger in International Law (Martinus Nijhoff Publishers, Boston, 2008) pp. 536–537.
ibid, p. 532. See e.g. UN General Assembly, Resolution 3314: ‘Definition of Aggression’ (4 December 1974) U.N. Doc. A/RES/3314, Articles 1 and 3.
UN SC Resolution 1368 (Condemnation of 11 September attacks against United States) (12 September 2001) U.N. Doc. S/RES/1368.
U.N. Doc. S/2001/946 (Letter from usa to unsc) (n 77).
U.N. Doc. S/2001/947 (Letter from UK to unsc) (n 77); unsc, ‘Letter dated 24 October 2001 from the Chargé d’affaires a.i. of the Permanent Mission of Canada to the United Nations addressed to the President of the Security Council (24 October 2001) U.N. Doc. S/2001/1005.
UN SC Resolution 1378 (on the situation in Afghanistan) (14 November 2001) U.N. Doc. S/RES/1378, para. 5.
See for instance unsc, ‘Letter dated 23 November 2001 from the Permanent Representative of Australia to the United Nations addressed to the President of the Security Council’, [23 November 2001] U.N. Doc. S/2001/1104; unsc, ‘Letter dated 23 November 2001 from the Permanent Representative of France to the United Nations addressed to the President of the Security Council’ [23 November 2001] U.N. Doc. S/2001/1103; and unsc, ‘Letter dated 29 November 2001 from the Permanent Representative of Germany to the United Nations addressed to the President of the Security Council’ [29 November 2001] UN Doc S/2001/1127.
See Michael N. Schmitt, Counter-Terrorism and the Use of Force in International Law (Marshall Center Papers, no 5, 2002) p. 48, and Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) p. 440 (“it was generally accepted that the 9/11 attacks were not attributable to the Taleban within the meaning of the ilc dasr [Draft Articles on State Responsibility]”). See, however, Dinstein, War, Aggression and Self-Defence (n 12) p. 261, and Boddens Hosang, ‘Self-Defence in Military Operations’ (n 11) pp. 39–40.
See also Gill, ‘The Temporal Dimension of Self-Defence’ (n 45) p. 118.
Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, I.C.J. Rep 2004, p. 136, para 139.
ibid, Separate Opinion of Judge Higgins, para. 33.
ibid, Separate Opinion of Judge Koojimans, para. 35.
ibid, Declaration by Judge Buergenthal, para. 6.
icj Armed Activities Case (n 68) Separate Opinion of Judge Simma, para 11. In this case, the Court concluded that the preconditions for self-defence were not met, and therefore that it did not need to consider the issue of self-defence against non-state actors. ibid, Judgement, para. 147.
Schmitt, ‘Targeted Killings and International Law’ (n 82) p. 533.
Reflecting this new State practice, former UK Foreign and Commonwealth Office Legal Adviser Daniel Bethlehem has proposed 16 principles for the use of force against non-State actors. See Daniel Bethlehem, ‘Self-Defense Against an Imminent or Actual Armed Attack By Nonstate Actors’, 106(4) American Journal of International Law 770 (October 2012). Several books and articles have been written on the topic. See e.g. Monica Hakimi, ‘Defensive Force against Non-State Actors: The State of Play’, 91 International Law Studies 1 (2015), and Louise Arimatsu and Michael N. Schmitt, ‘Attacking “Islamic State” and the Khorasan Group: Surveying the International Law Landscape’, 53 Columbia Journal of Transnational Law Bulletin 1 (2014).
See e.g. unsc, Letter dated 11 January 2016 from the Permanent Representative of Denmark to the unsc, ‘Letter dated 3 June 2016 from the Permanent Representative of Norway to the United Nations addressed to the President of the Security Council’ [3 June 2016] UN Doc S/2016/513.
unsc, ‘Letter dated 23 September 2014 from the Permanent Representative of the United States of America to the United Nations addressed to the Secretary-General’ [23 September 2014] UN Doc S/2014/695. See also Brian Egan (Legal Adviser, U.S. Department of State), ‘International Law, Legal Diplomacy, and the Counter-isil Campaign: Some Observations’ (speech prepared for delivery on the 110th Annual Meeting of the American Society of International Law, Washington, DC, April 1, 2016) published in 92 International Law Studies 235 (2016).
See examples provided in Elena Chachko and Ashley Deeks, ‘Who is onboard with “unwilling or unable”?’, Lawfare (10 October 2016,
The test is set out e.g. in Bethlehem, ‘Self-Defense Against an Imminent or Actual Armed Attack By Nonstate Actors’ (n 97) principles 11 and 12. For an overview of States’ justifications for their operations against non-State actors on the territory of a non-consenting State, see Chachko and Deeks, ‘Who is onboard with “unwilling or unable”?’, ibid.
Schmitt, ‘Targeted Killings and International Law’ (n 82) p. 533.
According to Christine Gray, “The use of force to rescue nationals in a foreign state without the consent of that state is uncommon and has been practices by only a few states since the Second World War”. Gray, International Law and the Use of Force (n 16) p. 156. See also, Dinstein, War, Aggression and Self-Defence (n 12) pp. 255–259; and Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 213–249. This question is also relevant to the potential application of force by peacekeeping forces, however, as explained in Chapter 1, this will not be dealt with in this book. For information on this matter, see e.g. Geert-Jan Alexander Knoops, ‘The transposition of inter-state self-defense and use of force onto operational mandates for peace support operations’, in Roberta Arnold (ed): Law Enforcement Within the Framework of Peace Support Operations (brill, 2008) pp. 3–21.
Gray, International Law and the Use of Force, ibid, p. 157.
See e.g. icj Nicaragua Case (n 69) Merits, paras. 193–195 and 199 stating the customary rule of collective self-defence, and para 233, where it is stated that: “So far as El Salvador is concerned, it appears to the Court that while El Salvador did in fact officially declare itself the victim of an armed attack, and did ask for the United States to exercise its right of collective self-defence, this occurred only on a date much later than the commencement of the United States activities which were allegedly justified by this request”.
Ago, ‘Addendum to the Eight Report on State Responsibility’ (n 25) p. 69. See also Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 95ff.
Wilmshurst, ‘The Chatham House principles of international law on the use of force in self-defence’ (n 16) Principle C, p. 967.
See e.g. Dinstein, War, Aggression and Self-Defence (n 12) p. 231; and Brownlie, International Law and the Use of Force by States (n 16) pp. 377–378. See also Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 158–168, debating the existence of a requirement of an “animus aggressionis”, and Waldock, ‘The Regulation of the Use of Force’ (n 16) p. 493.
If the attack is unintentional and those attacking are lacking the necessary mental element for a crime of aggression, the attack itself still lacks lawful authority and remains unlawful. The attacked State may therefore still respond in self-defence. See also Chapter 8, note 23, where in the context of domestic criminal law it is noted that the force may be used in self-defence even when the attacker may not be criminally responsible for instance due to insanity or low age.
Some commentators, however, view this issue as an aspect of necessity: namely that the defensive measures must be limited to what is necessary to stop the ongoing attack. See e.g. Wilmshurst, ‘The Chatham House principles of international law on the use of force in self-defence’ (n 16) Principle C, p. 967.
For an example of the contrary view, see Gray, International Law and the Use of Force (n 16) p. 150. She also argues that “the different views on the scope of the right of self-defence will affect the scope of proportionality” (ibid, p. 150), and mentions anticipatory self-defence and the accumulation of events doctrine as examples which may result in a wider interpretation of proportionality. However, whether anticipatory self-defence is permitted is question of necessity, not proportionality, and if the proportionality relates to the intended result rather than the previous attack, it will not be affected by the accumulation of events debate.
As Ago explains: “What matters in this respect is the result to be achieved by the “defensive” action, and not the forms, substance and strength of the action itself. A limited use of armed force may sometimes be sufficient for the victim State to resist a likewise limited use of armed force by the attacking State, but this is not always certain.” Ago, ‘Addendum to the Eight Report on State Responsibility’ (n 25) p. 69. Not all agree that this functional approach should be applied, but contend instead that the defensive measures should be similar to the initial attack. See discussion in Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 110–116.
Dinstein, War, Aggression and Self-Defence (n 12) p. 233.
Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 114 and 116. For instance, Israel was criticised for using disproportionate force against Lebanese territory in response to several attacks by Hizbollah. See the UN Secretary General’s Press Release of 20 July 2006, ‘Secretary-General says ‘immediate cessation of hostilities’ needed in Lebanon, describes package aimed at lasting solution, in Security Council briefing’, U.N. Doc. SG/SM/10570-SC/8781, and Gray, International Law and the Use of Force (n 16) pp. 241–244.
As expressed in e.g. AP I (n 5) Articles 51(5)(b) and 57(2)(b).
Ago, ‘Addendum to the Eight Report on State Responsibility’ (n 25) p. 70. On the distinction between immediacy as in imminent threat and as a requirement intended to distinguish self-defence from armed reprisals, see further Gill, ‘The Temporal Dimension of Self-Defence’ (n 45) pp. 151–154, and Dinstein, War, Aggression and Self-Defence (n 12) pp. 205–206 (imminence) and 233–234 (immediacy). Not all adhere to this distinction. See for instance Schmitt, ‘Targeted Killings and International Law’ (n 82) pp. 535–538.
George P. Fletcher, Basic Concepts of Criminal Law (Oxford University Press, Oxford, 1998) p. 134. It was originally expressed in the context of criminal law, but is perceived as applicable in international law. See Fletcher and Ohlin, Defending Humanity (n 18) p. 90.
icj Nicaragua case (n 69) para 237: “these measures were only taken, and began to produce their effects several months after the major offensive of the armed opposition against the Government of El Salvador had been completely repulsed (January 1981) and the actions of the opposition considerably reduced in consequence. Thus it was possible to eliminate the main danger to the Salvadorian Government without the United States embarking on activities in and against Nicaragua. Accordingly, it cannot be held that these activities were undertaken in the light of necessity”.
See e.g. Maria Benvenuta Occelli, ‘Sinking the Caroline: Why the Caroline Doctrine’s Restrictions on Self-Defense Should Not Be Regarded as Customary International Law’, 4 San Diego International Law Journal 482 (2003), p. 482.
Dinstein, War, Aggression and Self-Defence (n 12) p. 268.
Schmitt, ‘Targeted Killings and International Law’ (n 82) p. 538.
Anthony Aust, Handbook of International Law (Cambridge University Press, NY, 2010) p. 211. See also Ruys, ‘Armed Attack’ and Article 51 of the UN Charter (n 16) pp. 74–83; and Dinstein, War, Aggression and Self-Defence (n 12) pp. 237–241.
See e.g., icj Armed Activities Case (n 68) paras 145 and 147.
Boddens Hosang, ‘Self-Defence in Military Operations’ (n 11) p. 43.
Albin Eser, ‘Article 31. Grounds for excluding criminal responsibility’, in Otto Triffterer, Comments on the Rome Statute of the International Criminal Court – Observer’s Notes, Article by Article (2nd ed, Beck/Hart, München, 2008) p. 879. According to Gill, “the right of States to exercise self-defence under international law cannot be compared to the domestic rights of individuals. Despite the common roots of the two variants in natural law doctrine, they are completely distinct, operating within totally different contexts and environments”. Gill, ‘The Temporal Dimension of Self-Defence’ (n 45) p. 152.
McCormack, ‘Self-Defence in International Criminal Law’ (n 65) pp. 244–245.
Massimo Scaliotti, ‘Defences before the international criminal court: Substantive grounds for excluding criminal responsibility – Part 1’, 1 International Criminal Law Review 111 (2001), p. 171; Kai Ambos, ‘Other grounds for excluding criminal responsibility’, in Antonio Cassese, Paola Gaeta, John R.W.D. Jones (eds.), The Rome Statute of the International Criminal Court – A commentary, Volume I (Oxford University Press, Oxford, 2002) pp. 158–159.
On the distinction between these two forms of self-defence, see McCormack, ‘Self-Defence in International Criminal Law’ (n 65) pp. 232–235.
See also Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 17.
ibid.
ibid, pp. 17–18.
See AP I (n 5) Articles 13(2), 65(3) and 67(1)(d) and Geneva Convention (I) for the Amelioration of the Condition of the Wounded and Sick in Armed Forces in the Field (GC I) [1949], Laws of Armed Conflict, printed in Schindler and Toman, The Laws of Armed Conflicts (n 5) pp. 459ff., Article 21(1), where it is set out that civil defence personnel and medical personnel may carry light individual weapons for self-defence purposes without losing their protected status. See also Henderson and Cavanagh, ‘Claiming self-defence on the battlefield’ (n 11) p. 76. Furthermore, according to Geneva Convention (iii) relative to the Treatment of Prisoners of War (GC iii) [1949], printed in Schindler and Toman, The Laws of Armed Conflicts, ibid, pp. 507ff., Article 42, in the case of a prisoner of war (pow) who attacks a guard, the use of weapons in response “must constitute an extreme measure”, resembling self-defence requirements. The relevance of self-defence to attacks by prisoners on their guards was confirmed e.g. in United States v. Erich Weiss and Wilhelm Mundo, pp. 149–150 (see also Section 6.3.1.2), and Prosecutor v. Radomir Vukovic and Zoran Tomic, Court of Bosnia and Herzegovina, Section I for War Crimes, Case no. X-KR-06/180–2, Judgement of 22 April 2010, § 435. For further discussion, see Gloria Gaggioli, Expert Meeting on the Use of Force in Armed Conflict: Interplay Between the Conduct of Hostilities and Law Enforcement Paradigms (icrc, Geneva, 2013,
See e.g. Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) p. 287. For a rare example of the contrary view, see Elies Van Sliedregt, Individual Criminal Responsibility in International Law (Oxford University Press, Oxford, 2012) p. 234, referring to “self-defence in the context of the laws of war”, that is, “self-defence by acts that are lawful under the rules of war”. See also p. 238.
McCormack, ‘Self-Defence in International Criminal Law’ (n 65) p. 236.
Rome Statute of the International Criminal Court [hereinafter: Rome Statute], opened for signature 17 July 1998, 2187 unts 3 (entered into force 1 July 2002), Article 31: ‘Grounds for excluding criminal responsibility’, Section 1(c).
See e.g. William A. Schabas, ‘General principles of criminal law in the International Criminal Court statute (Part iii)’, 6 European Journal of Crime, Criminal Law and Criminal Justice 84 (1998), p. 105, and McCormack, ‘Self-Defence in International Criminal Law’ (n 65) p. 236.
Ilias Bantekas, ‘Mundo and Weiss (case commentary)’, Part C: Cases, in Cassese, Antonio (ed), Oxford Companion to International Criminal Justice (Oxford University Press, Oxford, 2009) p. 828. See also Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) p. 1034, referring to “emerging rules of international criminal law based on comparative criminal law”.
Scaliotti, ‘Defences before the international criminal court’ (n 127) pp. 162–163. For examples of self-defence being considered in criminal law cases arising after the Second World War, such as the Chusaboro case, see also McCormack, Self-Defence in International Criminal Law (n 65) pp. 239–242 and Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) pp. 1004–1005.
United States vs. Erich Weiss and Wilhelm Mundo, Case No. 81 (United States General Military Government Court at Ludwigsburg, Germany, 9th-10th November, Law Reports of Trials of War Criminals, published for the United Nations War Crimes Commission by His Majesty’s Stationary Office, London, 1949) Vol. xiii, pp. 149–150.
ibid, p. 150.
Prosecutor v. Kordic and Cerkez (Judgement), Case No IT-95-14/2-T, icty, Trial Chamber, 26 Feb 2001, §827. See also discussion in §§576, 621, and 642.
ibid, §449.
ibid, paras. 449–451, confirmed in the Prosecutor v Kordic and Cerkez (Judgement), Case No. IT-95-14/2-A, icty, Appeals Chamber, 17 December 2004, para. 837.
Eser, ‘Article 31’ (n 125) p. 881. See also McCormack, ‘Self-Defence in International Criminal Law’ (n 65) p. 237 and Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) p. 1032.
“Psychological threats” presumably refers to oral threats, as opposed to physical. Ambos, ‘Other grounds for excluding criminal responsibility’, ibid, p. 1032. See also Eser, ‘Article 31’, ibid, p. 880.
See also McCormack, ‘Self-Defence in International Criminal Law’ (n 65) pp. 237–238, and Hannah Tonkin, ‘Defensive Force Under the Rome Statute’ 6(1) Melbourne Journal of International Law 86 (2005), pp. 98–99.
For those not so entitled, for instance civilian who are going to be collateral damage, the criminal defence of necessity may apply, to the extent the applicable domestic legislation permits the use of force under that defence.
McCormack, ‘Self-Defence in International Criminal Law’ (n 65 p). 238. See also Eser, ‘Article 31’ (n 125) p. 882; Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) p. 1032; and George P. Fletcher, ‘The Influence of the Common Law and Civil Law Traditions on International Criminal Law’, in Antonio Cassese (ed.), The Oxford Companion to International Criminal Justice (Oxford University Press, Oxford, 2009) pp. 106–107.
See also Tonkin, ‘Defensive Force Under the Rome Statute’ (n 146) p. 106.
Eser, ‘Article 31’ (n 125) p. 883.
ibid, p. 883.
Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) p. 1035.
Rome Statute (n 135) Article 31(1)(c).
Eser, ‘Article 31’ (n 125) p. 881.
Scaliotti, ‘Defences before the international criminal court’ (n 127) pp. 160, 166, 169–170.
Antonio Cassese et al., International Criminal law (Oxford University Press, Oxford, 2013) p. 212. See, however, Cryer, who contends that the practice of States and the un roe is to permit defence of mission essential property, and that Cassese’s criticism is therefore “a little harsh”. Robert Cryer, ‘Defences/Grounds for Excluding Criminal Responsibility’, in Robert Cryer et al. (eds.), An Introduction to International Criminal Law and Procedure (Cambridge University Press, 2010) pp. 409–410.
Eser, ‘Article 31’ (n 125) p. 881.
ibid, p. 882.
AP I (n 5) Article 54: “It is prohibited to attack, destroy, remove or render useless objects indispensable to the survival of the civilian population, such as foodstuffs, agricultural areas for the production of foodstuffs, crops, livestock, drinking water installations and supplies and irrigation works, for the specific purpose of denying them for their sustenance value to the civilian population or to the adverse Party, whatever the motive, whether in order to starve out civilians, to cause them to move away, or for any other motive”.
Cassese et al., International Criminal Law (n 156) p. 213.
AP I (n 5) Articles 51(5)(b) and 57(2)(b).
See also Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 179–180, where he argues that the provision must be interpreted in light of applicable human rights law, with the result that property may only be defended with lethal force in cases involving a real risk of death or serious bodily harm as a result of the attack on the property.
Eser, ‘Article 31’ (n 125) p. 882, criticising the icty Trial Chamber’s contention that “the provision takes into account the principle of military necessity”, in Prosecutor v Kordic and Cerkez (Judgement), Trial Chamber (n 141) §451.
Eser, ‘Article 31’, ibid, p. 882. See also Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) p. 1034, and Sliedregt, Individual Criminal Responsibility in International Law (n 133) p. 236.
Eser, ‘Article 31’, ibid, p. 883. See also Tonkin, ‘Defensive Force Under the Rome Statute’ (n 146) pp. 102–106.
Prosecutor v. Gotovina and others (Judgement Vol II), Case no. IT-06-90-T, icty, Trial Chamber, 15 April 2011, § 1730.
Scaliotti, ‘Defences before the international criminal court’ (n 127) p. 166.
A similar concern was voiced by the South African delegation, according to Scaliotti, ibid, p. 167.
AP I (n 5) Article 49(1) makes it clear that loac regulated all “acts of violence against the adversary, whether in offence or in defence”.
See e.g. Scaliotti, ‘Defences before the international criminal court’ (n 127) p. 171, Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) pp. 1033 and 1034; Cassese et al., International Criminal Law (n 156) p. 211, Eser, ‘Article 31’ (n 125) pp. 879–880, Mark Klamber, ‘Article 31(1)(b)’, Commentary on the Law of the International Criminal Court (clicc) (updated 30 June 2016,
The formulation in Article 31(1)(c) may also, as Cassese points out, be misread to imply that “the defensive character of the operation is at least a relevant, though not decisive, consideration”. However, this potential interpretation is rejected by Cassese and Eser. Cassese et al., International Criminal law, ibid, p. 211, and Eser, ‘Article 31’, ibid, pp. 879–880.
ibid, p. 880, footnote omitted.
ibid, p. 880. See also above, Section 1.3.2.2. The relationship between the two forms of self-defence is briefly presented in Section 6.2.4, while the tendency of overreliance on self-defence during military operations is discussed in Section 8.3.2.
Scaliotti, ‘Defences before the international criminal court’ (n 127) p. 171, referring to Report of the Working Group on General Principles of Criminal Law, U.N. Doc. A/CONF.183/C.1/WGGP/L.4/Add.1/Rev.1, 2 July 1998, footnote 12 to Article 31(1)(c). See also Eser, ‘Article 31’ (n 125) p. 882.
Rome Statute (n 135) Preamble.
icc, Activation of the jurisdiction of the Court over the crime of aggression, Resolution ICC-ASP/16/Res.5, adopted at the 13th plenary meeting, on 14 December 2017, by consensus.
See e.g. Schabas, ‘General Principles of Criminal Law’ (n 136) p. 108: “Its relevance (…) seems remote, at best, at least with respect to those large-scale crimes committed by planners and organizers that are at the heart of the Court’s raison d’être.” See also Scaliotti, ‘Defences before the international criminal court’ (n 127) pp. 170 and 172, and Sliedregt, Individual Criminal Responsibility in International Law (n 133) pp. 235 and 237–238.
McCormack, ‘Self-Defence in International Criminal Law’ (n 65) p. 234. See also Sliedregt, Individual Criminal Responsibility in International Law, ibid, pp. 236–237.
See also John Cerone, ‘Is there a human right of self-defense?’, 2 Journal of Law, Economy and Policy 319 (2006), p. 327.
ibid, p. 328.
European Convention for the Protection of Human Rights and Fundamental Freedoms (echr)[1950], as amended by Protocols Nos. 11 and 14, ets 5, Article 2(2). Other human rights instruments recognise the right to use defensive force to protect their right to self-determination, which is akin to self-defence, but a much more narrow right. See Article 20(2) of the African Charter on Human and Peoples’ Rights (“Banjul Charter”), Organization of African Unity, 27 June 1981, CAB/LEG/67/3 rev. 5, 21 I.L.M. 58 (1982), and Article 2(4) of the Arab Charter on Human Rights, League of Arab States, 15 September 1994. Similarly, the Preamble to the Universal Declaration of Human Rights, Adopted by General Assembly Resolution 217 A(iii) of 10 December 1948 (
See Section 4.2.2.
See e.g. Stephens, ‘ROE and the Concept of Unit Self-Defense’ (n 79) p. 128; Mark David Maxwell, ‘Individual Self-Defense and the Rules of Engagement: Are the Two Mutually Exclusive?’, 41 Mil. L. & L. War Rev. 39 (2002), p. 46; David B. Kopel, Paul Gallant, and Joanne D. Eisen, ‘The Human Right of Self-Defense’, 22 Brigham Young University Journal of Public Law 43 (2007), p. 44; and Cerone, ‘Is there a human right of self-defense?’(n 179).
See e.g. Kopel, Gallant and Eisen, ‘The Human Right of Self-Defense’, ibid, pp. 174–177. The issue is particularly debated in the usa, both in academic literature, in courts and in the media. See e.g. District of Columbia v. Heller, 128 S. Ct. 2783, 2799 (2008) (“There seems to us no doubt … that the Second Amendment conferred an individual right to keep and bear arms”).
UN Special Rapporteur Barbara Frey, Prevention of Human Rights Violations Committed with Small Arms and Light Weapons, Final Report Submitted to the UN Sub-Commission on the Promotion and Protection of Human Rights, UN Doc A/HRC/Sub.1/58/27 (27 July 2006), available at (
ibid, pp. 8 and 14. For a critique of the report, see Kopel, Gallant and Eisen, ‘The Human Right of Self-Defense’, (n 183).
Boddens Hosang, ‘Force Protection, Unit Self-Defence, and Personal Self-Defence’ (n 15) p. 483, §24.08.
See discussion in Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 78–83. He cites an Australian Defence Force Publication as a rare example of domestic norms referring to self-defence as an inherent right.
ibid, p. 89.
Frey, Prevention of Human Rights Violations Committed with Small Arms and Light Weapons (n 185) p. 10.
See discussions in Section 4.2 on the right to life and Section 8.2 on the use of force in self-defence by military forces.
Cerone, ‘Is there a human right of self-defense?’ (n 179) p. 322.
Except when a case is tried before the International Criminal Court, in which case the self-defence provision would be found in the Rome Statute, or in the case of icty and ictr, customary law as set out in previous decisions by their tribunals.
McCann and others v. the UK, App. No. 18984/91 (ECtHR, 27 September 1995), paras. 153–155.
un hrc, ‘Report of the Special Rapporteur on extrajudicial, summary or arbitrary executions, Christof Heyns’, UN Doc. A/HRC/26/36 [1 April 2014] para. 72; and UN Human Rights Committee (hrc), Draft General Comment No. 36 – Article 6: Right to Life [hereinafter Draft General Comment 36], [19 October–6 November 2015], UN Doc CCPR/C/GC/R.36/Rev.2, para. 18. See also Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 178–180.
See e.g. Leverick, Killing in Self-Defence (n 26) p. 183; David Harris, ‘The Right to Life under the European Convention on Human Rights’, 1 Maastricht Journal of European and Comparative Law 122 (1994), p. 133, and Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 175–178 and 255–257.
Prosecutor v. Kordic and Cerkez (Judgement), Trial Chamber (n 143) §451.
Statute of the International Court of Justice, 18 April 1946 [hereinafter: icj Statute], accessed at
Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 58–59.
ibid, pp. 19–20.
Cerone, ‘Is there a human right of self-defense?’ (n 179) pp. 326–327, where the issue is raised in relation to a customary human right of self-defence. He concludes that there is insufficient opinion juris to support the existence of such a customary rule. For an example of the contrary position, see Geert-Jan Alexander Knoops, Defenses in Contemporary International Criminal Law (Martinus Nijhoff Publishers, Leiden, 2008) pp. 73–74.
The inclusion of the use of force to protect property not essential for a person’s survival was, as explained above, quite controversial, and this aspect is therefore less likely to reflect a customary rule on self-defence.
Haggenmacher, for instance, refers to the passage as “the fountainhead of this whole tradition of self-defence as a natural right”. Peter Haggenmacher, ‘Self-defence as a general principle of law and its relation to war’, in Arthur Eyffinger, Sam Muller, and Alan Stephens (eds.), Self-defence as a Fundamental Principle (Hague Colloquium in Fundamental Principles of Law, Hague Academic Press, 2009) p. 5. See also Gentili, De Jure Belli Libri Tres (n 48) p. 59 [94].
Cicero, ‘Pro Milone’ (n 1) p. 186, §§10–11 (page number omitted). This passage has been referred to as “the fountainhead of this whole tradition of self-defence as a natural right.” Haggenmacher, ‘Self-defence as a general principle of law and its relation to war’, ibid, p. 5.
Thomas Aquinas, Summa Theologica – The Complete Edition (first published 1265–1274, translation published by Catholic Way Publishing, 2014, available at
Gentili, De Jure Belli Libri Tres (n 48) Book I, Chapter xiii, p. 58 [94].
Samuel Pufendorf, De Jure Naturae et Gentium Libri Octo (On The Law of Nature and Nations: Eight Books) (first published 1688, translation by C.H Oldfather and W. A. Oldfather, The Classics of International Law No 17 Vol 2, Oxford University Press, Oxford, 1934) Book II, Chapter V, §1, pp. 264–265 [182].
ibid.
Vattel, Le droit des gens (n 48) Book iii, Chapter XV, § 231, at p. 230.
William Blackstone, Commentaries on the Laws of England, Oxford 1765–1769, Book iii, Chapter 1, 1, p.4, cited in Haggenmacher, ‘Self-defence as a general principle of law and its relation to war’ (n 203) p. 4.
For a useful overview, see Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 31–34 and 40–47, considering Judo-Christian Tradition; Islam and the Sharia; African customary or ‘traditional’ legal systems; Confucianism, Taoism and traditional Chinese law; Hinduism; and Buddhism.
ibid, pp. 41 and 46.
Aquinas, Summa Theologica (n 205) Part II.2 Question 64, Article 7, Objection 5, citing “Cap. Significasti, De Homicid. volunt. vel casual.”
Grotius, De jure belli ac pacis libri tres (n 48) p. 173.
ibid, p. 175.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 34.
ibid, p. 35.
See also ibid, p. 27.
Or its predecessor, the Permanent Court of International Justice.
Pellet, ‘Article 38’ (n 69) p. 832.
Antonio Cassese, International Law (2. ed., Oxford University Press, Oxford, 2005) p. 189, at footnote 3.
James Crawford, Brownlie’s Principles of Public International Law (Oxford University Press, Oxford, 2012) p. 34. The term ‘civilized nations’ should be read as all States; even at the time of drafting all nations were considered civilised. Pellet, ‘Article 38’ (n 69) pp. 836–837.
South West Africa, Second Phase, Judgment, I.C.J. Reports [1966] 6, Dissenting opinion of Judge Tanaka p. 250, at p. 298.
Pellet, ‘Article 38’ (n 69) p. 834, fn. 725.
ibid, p. 837, original emphasis.
ibid, p. 834.
ibid, pp. 833–834.
Crawford, Brownlie’s Principles of Public International Law (n 222) p. 37.
Prosecutor vs. Furundžija (Judgement), Case No. IT-95-17/1-T, icty, Trial Chamber, 10 December 1998, p. 72, § 183, discussed in Cassese, International law (n 221) p. 189, fn. 3.
Cerone, ‘Is there a human right of self-defense?’ (n 179) p. 327.
Jens Ohlin, ‘Self-Defence’, in Antonio Cassese (ed.), The Oxford Companion to International Criminal Justice (Oxford University Press, Oxford, 2009) p. 507.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 73.
Frey, Prevention of Human Rights Violations Committed with Small Arms and Light Weapons (n 185) p. 17, endnote 22.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 89.
See un ilc, ‘Document A/3623: Report of the International Law Commission covering the work of its ninth session, 23 April-28 June 1957’, UN Doc. A/CN.4/SER.A/1957/Add.1 (1957), Yearbook of the International Law Commission 1957, Vol. II, Part Two, p. 131, at p. 138, commentary to Article 22. See further Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 71–73.
Hessbruegge, Human Rights and Personal Self-Defense, ibid, p. 76.
nato, MC 362/1 (n 14) p. 4.
ibid.
See further Section 3.5 and Chapter 11 on the nato hostile act and hostile intent roe.
Henderson and Cavanagh, ‘Claiming self-defence on the battlefield’ (n 11) p. 76. See also Gary P. Corn, ‘Developing Rules of Engagement: Operationalizing law, policy and military imperatives at the strategic level’, in Geoffrey S. Corn, Rachel E. VanLandingham and Shane R. Reeves (eds.), U.S. Military Operations – Law, Policy and Practice (Oxford University Press, Oxford, 2016) p. 227, fn. 91.
Nigel D. White, ‘Defending Humanity: When Force is Justified and Why by George P. Fletcher and Jens David Ohlin’ (n 46) p. 385.
Status of Forces Agreement is an agreement between two or more States, usually one or more sending State and a receiving State, that among others regulate the question of jurisdiction over the troops if they commit an offence. Naturally such agreements are only possible to reach such agreements if the States are cooperating, and are thus unlikely to exist between States involved in an armed conflict. Also, sofas may be time consuming to negotiate, and may therefore not be available for rapid deployments. For information on nato sofa, see Sherrod Lewis Bumgardner et al., NATO Legal Deskbook (act Staff Element Europe, Belgium, 2010, available at
See Section 4.2.1.
On the ad bellum roots of the sroe self-defence construct, see Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) pp. 17–20. See also Henderson and Cavanagh, ‘Claiming self-defence on the battlefield’ (n 11) p. 75. Unit self-defence is examined in Section 8.3.3.
Maxwell, ‘Individual Self-Defense and the Rules of Engagement’ (n 183) p. 44. See also Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) pp. 4 and 6.
Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) p. 19.
McCormack, ‘Self-Defence in International Criminal Law’ (n 65) p. 235 and Eser, ‘Article 31’ (n 125) p. 879.
As mentioned in Section 6.3.1.5, personal self-defence may also exist in the international law of the sea and of diplomatic relations, however, these are less relevant to the current context due to the focus on armed conflict operations.
See also Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) p. 305: “the root of European soldiers’ self-defense rights is the extraterritorial application of domestic law”.
For a useful and detailed comparative analysis of the U.S. French, German and British approaches to self-defence, see ibid, pp. 295–318, and Gaston, Erica L., When Looks Could Kill (n 6) pp. 22–50.
The main exception to this is the U.S. See also Gill et al. ‘General Report’ (n 16) pp. 151–152.
See also Hessbruegge, Human Rights and Personal Self-Defense (n 10). 67.
See e.g. Boddens Hosang, ‘Force Protection, Unit Self-Defence, and Personal Self-Defence’ (n 15) p. 489, §24.14; Knoops, Defenses in contemporary international criminal law (n 201) p. 63; Ohlin, ‘Self-defence’ (n 231) p. 506; Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 63; and Victoria Nourse, ‘Self-defence’, in Markus D. Dubber and Tatjana Hörnle (eds.), The Oxford Handbook of Criminal law (Oxford University Press, Oxford, 2014) p. 616.
For iacs, the right to participate in hostilities is set out in treaty law, but there is no similar treaty rule in niacs. Still, State practice indicates that States consider the acts of their forces lawful also under niacs. See further 5.1.2.
See also Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 101. Note, however, that defensive force under loac is sometimes referred to as self-defence, although this is not the legal concept of self-defence but rather a separate operational concept. See further 8.3.
See further Section 5.1.
See e.g. Krupp et al., Judgment of 31 July 1948, U.S. Military Tribunal Nuremberg, in Trials of War Criminals Before the Nuremberg Military Tribunals, Vol. IX, available at
Ohlin, ‘The Doctrine of Legitimate Defense’ (n 47) p. 138. See also Ohlin, ‘Self-defence’ (n 231) p. 506.
Fletcher, Basic Concepts of Criminal Law (n 117) p. 133.
Ohlin, ‘The Doctrine of Legitimate Defense’ (n 47) p. 138, and Fletcher, Basic Concepts of Criminal Law, ibid, p. 133. Note, however, that the UK Criminal Justice and Immigration Act of 2008 (
Fletcher, Basic Concepts of Criminal Law, ibid, p. 133.
ibid, and Ohlin, ‘Self-defence’ (n 231) p. 506.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 63.
ibid, p. 65.
Fletcher, Basic Concepts of Criminal Law (n 117) p. 134.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 66.
ibid.
ibid, pp. 64, 133–139 and 198. See also Nourse, ‘Self-defence’ (n 253) p. 617; and Sliedregt, Individual Criminal Responsibility in International Law (n 133) p. 239. For national examples, see e.g. the American Law Institute, Model Penal Code: Official Draft and Explanatory Notes, Complete Text of Model Penal Code as Adopted at the 1962 Annual Meeting of the American Law Institute at Washington, D.C., May 24, 1962, The Institute, Philadelphia, 1985, Section 3.04(1) cf. Section 3.09(2); United States Manual for Courts-Martial (mcm), 2016 Edition (available at
Unfortunately, the defence of mistake is beyond the scope of this book. For a useful discussion, see e.g. Fletcher, Basic Concepts of Criminal Law (n 117) pp. 148–167, and Leverick, Killing in Self-Defence (n 26) pp. 159–176.
Lov om straff (Straffeloven) (Norwegian Penal Code of 1905), LOV-2005-05-20-28, §5.
Criminal defences are categorised as either justification and excuse. According to Cassese, they are “distinguished by their rationales and consequences”. Cassese et al., International Criminal Law (n 156) p. 210. Because this is of limited impact on the current discussion of application of personal self-defence in the context of military operations during armed conflict, the question whether self-defence is a justification or an excuse will not be examined. The issue is extensively dealt with in academic writing. For a selection, see e.g. Leverick, Killing in Self-Defence (n 26) pp. 13–41; Albin Eser, ‘Justification and Excuse’, 24 American Journal of Comparative Law 621 (1976); Krebs, Beatrice, ‘Justification and Excuse in Article 31(1) of the Rome Statute’, 2(3) Cambridge Journal of International and Comparative Law 382, (2013); and Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 59–63.
The distinction is also extensively discussed in relation to the Rome Statute of the icc. For instance, Fletcher has criticised Article 31 for failing to make a distinction between justification and excuse. Fletcher, ‘The Influence of the Common Law and Civil Law Traditions on International Criminal Law’ (n 148) p. 105. Others argue that the Article “contains classic elements of self-defence as a justification.” See e.g. Krebs, ‘Justification and Excuse in Article 31(1) of the Rome Statute’, ibid, p. 397.
See e.g. Gill et al. ‘General Report’ (n 16) p. 157.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 60–61.
ibid, pp. 59–60.
According to Barbra Frey, no such right exists: “There is not [sic] evidence however that States have enacted self-defence as a freestanding right under their domestic laws, nor is there evidence of opinio juris that would compel States to recognize an independent, supervening right to self-defence that they must enforce in the context of their domestic jurisdictions as a supervening right.” Frey, Prevention of Human Rights Violations Committed with Small Arms and Light Weapons (n 185) p. 9.
Gill et al. ‘General Report’ (n 16) p. 157.
See also e.g. Haggenmacher, ‘Self-defence as a general principle of law and its relation to war’ (n 203) pp. 15–16. Although he states that it is an absolute right, the concept referred to is that of notwehr or légitimate défense.
See also Boddens Hosang, Rules of Engagement (n 27) pp. 118–119 and Gill et al. ‘General Report’ (n 16) p. 157. The exceptional nature of self-defence in a more general context is also discussed in Fletcher and Ohlin, Defending Humanity (n 18) pp. 30–45.
See e.g. Daniel D. Nsereko, ‘Arbitrary Deprivation of Life: Controls of Permissible Deprivations’, in B. G. Ramcharan (ed.), The Right to Life in International Law (Martinus Nijhoff Publishers, Dordrecht/Boston/Lancaster, 1985) p. 245.
See e.g. Norwegian Penal Code (n 270) §196, which also provide as an exception the risk of being charged with acting unlawfully: “§ 196. Plikt til å avverge et straffbart forhold.\Med bot eller fengsel inntil 1 år straffes den som unnlater gjennom anmeldelse eller på annen måte å søke å avverge en straffbar handling eller følgene av den, på et tidspunkt da dette fortsatt er mulig og det fremstår som sikkert eller mest sannsynlig at handlingen er eller vil bli begått. Avvergingsplikten gjelder uten hensyn til taushetsplikt og gjelder straffbare handlinger som nevnt i\§§ 111, 113, 115, 117, 119, 121, 123, 128, 129, 138, 139, 140, 141, 142, 143, 144, 192, 193, 194, 223, 239, 255, 256, 259, 274, 275, 279, 282, 283, 288, 291, 295, 299, 312, 314, 327, 329, 355 og 357,\militær straffelov §§ 50, 52 eller 96, eller\sikkerhetsloven § 18 a, jf. § 31 fjerde led\Ved overtredelse av §§ 312 eller 314 gjelder avvergingsplikten bare når den fornærmede er under 16 år.\Brudd på avvergingsplikten straffes ikke når\handlingen det er tale om å avverge ikke har kommet så langt som til straffbart forsøk, jf. § 16, eller\plikten ikke kunne oppfylles uten å utsette ham selv, hans nærmeste eller noen uskyldig for siktelse eller tiltale eller fare for liv, helse eller velferd.”
On the question of extraterritorial application of human rights, see Section 4.2.3.
See examples in Section 6.3.2.3.
Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 102–103.
ibid, p. 100.
See also ibid, pp. 100–102. Not all States recognise the existence of such a duty. The Use of Force in Canadian Forces Operations, for instance, declares on p.2–2 that “there is no obligation to use force in self-defence”. Canadian Forces, Use of Force for CF Operations (Joint Publication 5.1, Document B-GJ-005-501/FP-001, issued under the authority of the Chief of the Defence Staff, 2008).
U.S. Chairman of the Joint Chiefs of Staff (cjcs), Standing Rules of Engagement (SROE)/Standing rules for the use of force (SRUF) for U.S. Forces [hereinafter: SROE/SRUF] (cjcs Instruction 3121.01B, 13 June 2005) p. A-3.
Corn, ‘Developing Rules of Engagement’ (n 240) p. 216, and Stephens, ‘ROE and the Concept of Unit Self-Defense’ (n 79) pp. 128–129.
See also Henderson and Cavanagh, ‘Claiming self-defence on the battlefield’ (n 11) pp. 75–76, and Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) pp. 20–23 and 50.
On the use of defensive force by law enforcement officials, see the detailed examination in Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 91–216.
See discussion on the right to life of military forces in Section 4.2. See also ibid, p. 68.
See Section 8.2.
See e.g. Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) especially pp. 25–31.
Gaggioli, The use of force in armed conflict (n 132) pp. 11–12.
echr (n 181) Article 2(2) sets out three situations where the use of force may be lawful if absolutely necessary: (a) in defence of any person from unlawful violence; (b) in order to effect a lawful arrest or to prevent the escape of a person lawfully detained; (c) in action lawfully taken for the purpose of quelling a riot or insurrection. The contention by Corn, that “the law is not so rigid as to exclude other state interests as equally legitimate” (Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) p. 51) will therefore not apply to those nato States that are party to the echr.
According to Hessbruegge, “ [t]he basic tenets for law enforcement agent’s use of defensive force appear to be essentially the same as those found in domestic self-defense provisions across the world”, although international human rights law may assign “particular features to each of these requirements”. Hessbruegge, Human Rights and Personal Self-Defense (n 10) p. 124. These additional features arise from the role of law enforcement personnel as State agents, and will therefore also apply to the use of force by military personnel.
Corn, ‘Public Authority to Use Force in Military Operations’ (n 19) e.g. p. 27.
ibid, p. 50.
See also Section 5.1.2 regarding the concept ‘lawful acts of war’.
See e.g. McCann and Others v. the UK (n 194) para. 294. See further discussion in Section 4.2.2
For a detailed analysis, see Hessbruegge, Human Rights and Personal Self-Defense (n 10) pp. 202–215.
On the question of extraterritorial application of human rights, see Section 4.2.3.
§13 of the Danish Criminal Code Order No. 909 of September 27, 2005, as amended by Act Nos. 1389 and 1400 of December 21, 2005 (translation available at
See also Danish Ministry of Defence/Defence Command Denmark, Military Manual on international law relevant to Danish armed forces in international operations [hereinafter: Danish Military Manual] (Rosendahls, København, 2016,
ibid, p. 130.
Frits Kalshoven and Thyla Fontein, ‘Some Reflections on Self-Defence as an Element in Rules of Engagement’ in Mariëlle Matthee etc. (eds.), Armed Conflict and International Law: In Search of the Human Face (tmc Asser Press, The Hague, 2013) p. 108.
Horvat and Benatar (eds.), Legal Interoperability (n 23) ‘National Reports: Pays-Bas/Netherlands’, p. 207.
Catherine Elliot, ‘France’, in Markus Dirk Dubber and Kevin Jon. Heller, The Handbook of Comparative Criminal Law (Stanford University Press, 2010) pp. 223–224. The application of the French Criminal Code as the standard for individual or unit self-defence by military forces is confirmed by the Centre Interarmees de Concepts, de Doctrines et d’Experimentations, Ministere de la Defense, DIA – 5.2: L’Usage de la Force en Operation Militaire se Deroulant a l’Exterieur du Territoire National [25 July 2006] p. 14, and État-Major des Armees, Division Emploi 1, PIA – 5.2: Directive Interarmees Sur l’Usage de la Force en Operation Militaire se Deroulant a l’Exterieur du Territoire National [25 July 2006] p. 34.
Article 122–5, first para, of the French Penal Code (translation available at
See also Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) p. 298, citing Centre Interarmees de Concepts, de Doctrines et d’Experimentations, Ministere de la Defense, DIA – 5.2: L’Usage de la Force en Operation Militaire se Deroulant a l’Exterieur du Territoire National [25 July 2006] p. 14.
Article 122–5, second para, of the French Penal Code (n 308).
Elliot, ‘France’ (n 307) p. 225, citing “Raisonnablement croire”: Crim. 21 février 1996, Bulletin des Arrets de la Cour de Cassation, 84, observations Bouloc; Revue de Science Criminelle, 1996, 849.
Article 122–7 of the French Penal Code (n 308).
Article L4123-12 of the French Code of Defense (available at
See e.g. Giles Castel, ‘Self-defence: A French perspective’, in 36 NATO Legal Gazette 41 (2005).
Article L. 435-1, French Law on Public Security, 28 February 2017 (available at
Thomas Weigend, ‘Germany’, in Markus Dirk Dubber and Kevin Jon Heller, The Handbook of Comparative Criminal Law (Stanford University Press, 2010) p. 268.
Section 32 of the German Criminal Code, translated by Prof. Dr. Michael Bohlander, 2016 juris GmbH, Saarbrücken (available at
Defence of others may also be referred to as ‘nothilfe’, as is emphasised e.g. in the presentation of German self-defence law in Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) pp. 298–299, however, there is no separate legal authority for this concept and it may also be considered a subset of ‘notwehr’. The concept of ‘nothilfe’ will therefore not be treated separately.
See e.g. Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) p. 1034, fn. 180.
Weigend, ‘Germany’ (n 316) p. 270.
ibid.
Section 33 of the German Criminal Code (n 317). See also Krebs, ‘Justification and Excuse in Article 31(1) of the Rome Statute’ (n 271) pp. 394–395.
Ambos, ‘Other grounds for excluding criminal responsibility’ (n 127) pp. 1034–1035.
Theodor Lencker and Walter Perron, ‘§32’, notes 43-61b, in Adolf Schönke and Horst Schröder (eds.), Strafgesetzbuch Kommentar (Beck, Munich, 2006, 27th ed.), cited in Weigend, ‘Germany’ (n 316) p. 271.
Fletcher, Basic Concepts of Criminal Law (n 117) p. 136.
The Norwegian Military Penal Code (Militær Straffelov), lov-2016-04-22-3.
Section 18, first paragraph, Norwegian Penal Code (n 270). Original text: “§ 18. Nødverge\En handling som ellers ville være straffbar, er lovlig når den\blir foretatt for å avverge et ulovlig angrep,\ikke går lenger enn nødvendig, og\ikke går åpenbart ut over hva som er forsvarlig under hensyn til hvor farlig angrepet er, hva slags interesse som angrepet krenker, og angriperens skyld.”
The rule applies equally to situations of self-defence, to effect a lawful arrest or to prevent the escape of a person lawfully remanded or detained, see Section18, second paragraph, Norwegian Penal Code.
This requirement was emphasised in a post-WW2 trial against the owner of a garage who was the victim of saboteurs from the Norwegian resistance movement. The court concluded that he did not have a right to act in self-defence because the saboteurs were acting in accordance with Norwegian interests and were therefore considered to be acting lawfully, something the garage owner knew. Rt. 1948 s. 75, cited in Johs Andenæs, Alminnelig strafferett (5.ed, Universitetsforlaget, Oslo, 2004) p. 163.
Ståle Eskeland, Strafferett (5. ed. by Alf Petter Høgberg, Cappelen Damm Akademiske, Oslo, 2017) p. 264.
Ot.prp.nr.90 (2003–2004) Om lov om straff (straffeloven) (Proposition Concerning the law on penalties (penal code)), p. 420.
ibid, pp. 420–421.
Sections 80(d) and 81(b) of the Norwegian Penal Code (n 270).
The effects caused by the self-defence act on innocent bystanders will be assessed under the principle of necessity, as regulated in Section 17 of the Norwegian Penal Code (n 270). Thomas Frøberg, Alminnelig strafferett i et nøtteskall (Gyldendal Juridisk, Oslo, 2016) p. 104.
Norwegian Armed Forces, Manual i krigens folkerett (Trans: Manual of the Law of Armed Conflict), issued under the authority of the Chief of the Defence, [2013] p. 281.
Note that the laws considered only apply to England, Wales and Northern Ireland.
See Palmer v R [1971] AC 814 (approved in R v McInnes, 55 Cr App R 551) at pp. 831–832 where Lord Morris stated that “It is both good law and good sense that a man who is attacked may defend himself. It is both good law and good sense that he may do, but only do, what is reasonably necessary”.
Section 76(1) of the Criminal Justice and Immigration Act of 2008 (n 260). Section 76 also applies to the use of force in the prevention of crime or making arrest.
Section 3(1) of the Criminal Law Act 1967 (
Section 76(2) of the Criminal Justice and Immigration Act of 2008 (n 260).
Ormerod et al., Smith and Hogan’s Criminal Law (n 56) p. 429.
Section 76(3–7) of the Criminal Justice and Immigration Act of 2008 (n 260) as updated by Legal Aid, Sentencing and Punishment of Offenders Act 2012 Section 148 and the Crime and Courts Act 2013 Section 43.
There is no requirement that genuine belief in the need to use force is reasonable. This has been argued to be contrary to echr Article 2 (n 181), for instance by Leverick, Killing in Self-Defence (n 26) pp. 183–190. Others argue that the echr does not demand a change to this test, see for instance Ormerod et al., Smith and Hogan’s Criminal Law (n 56) pp. 437–440.
Ormerod, et al., Smith and Hogan’s Criminal Law, ibid, pp. 444–445.
See also ibid, pp. 430–432 on the subjective and objective elements of self-defence. Note that the use of defensive force in the so-called householder case in specifically dealt with in the Crime and Courts Act 2013 Section 43 (
Section 76(6A) of the Criminal Justice and Immigration Act of 2008 (n 260). See also Ormerod et al., Smith and Hogan’s Criminal Law, ibid, p. 444.
Ormerod et al., Smith and Hogan’s Criminal Law, ibid, pp. 445–446.
See e.g. Kenlin and Another v Gardiner and Another, Divisional Court, 1 November 1966, [1967] 2 W.L.R. 129, [1967] 2 Q.B. 510, p. 518. See also Law Commission Report No.218, Legislating the Criminal Code: Offences Against the Person and General Principles, 1993 (
Ormerod et al., Smith and Hogan’s Criminal Law (n 56) pp. 443–444.
Section 76(2) of the Criminal Justice and Immigration Act of 2008 (n 260).
Ormerod et al., Smith and Hogan’s Criminal Law (n 56) p. 444.
ibid, p. 447.
Law Commission Report No.218 (n 347) para 33.6, p. 60, and Clause 27(1) of the proposed Criminal Law Bill in the report.
See e.g. Bici v. Ministry of Defence [2004], ewhc 786 (QB), ildc 100.
Attorney-General for Northern Ireland’s Reference (No. 1 of 1975) (1977) AC 105.
For instance, while the Connecticut defence of person rule states that self-defence is justified if the use of force could be avoided by retreating, the Florida rule stresses that there is no duty to retreat. See Connecticut General Statutes § 53a-19(b)(1) (
Self-defence is regulated in Sections 3.04 (self), 3.05 (others), and 3.06 (property). U.S. Model Penal Code (n 268). For a commentary on the mpc defences, see e.g. Paul H. Robinson, ‘United States’, in, Markus Dirk Dubber and Kevin Jon. Heller, The Handbook of Comparative Criminal Law (Stanford University Press, 2010) especially pp. 582–583.
Merriam, ‘Natural Law and Self-Defense’ (n 47) p. 72. See also Horvat and Benatar (eds.), Legal Interoperability (n 23) ‘National Reports: United States’, p. 195.
Uniform Code of Military Justice (ucmj), 64 Stat. 109, 10 U.S.C. Chapter 47 (
U.S. Manual for Courts-Martial, rcm 916(b)(1) (n 268) p. II-115: “the prosecution shall have the burden of proving beyond a reasonable doubt that the defense did not exist”.
U.S. Manual for Courts-Martial, ibid, rcm, pp. II-116–117.
ibid, rcm, p. II-116.
See also U.S. Department of Army Pamphlet 27–9, Military Judges’ Benchbook, Headquarters, Department of the Army, Washington, DC, 10 September 2014, pp. 965–974.
ibid, p. 966.
Merriam, ‘Natural Law and Self-Defense’ (n 47) p. 74.
See e.g. U.S. Manual for Courts-Martial (n 268) rcm 916(e)(1)(A), p. II-116, and U.S. Military Judges’ Benchbook (n 362) p. 965.
U.S. Military Judges’ Benchbook, ibid, p. 978.
ibid, p. 977.
U.S. cjcs, sroe/sruf (n 286) p. A-3.
ibid. See for instance Merriam, ‘Natural Law and Self-Defense’ (n 47) pp. 76–87; Eric D. Montalvo, ‘When Did Imminent Stop Meaning Immediate? Jus in bello Hostile Intent, Imminence and Self-Defense in Counterinsurgency’, Army Lawyer, August 2013, p. 24, pp. 24–34, and Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’ (n 2) pp. 310–314.
See e.g. a presentation of this view in Gaston, ‘Reconceptualizing Individual or Unit Self-Defense’, ibid, pp. 296–297.
ibid, p. 303, citing United States v. Behenna, 71 M.J. 228 (2012) and United States v. Holmes, 2010 cca Lexis 497 (2910).
ibid, pp. 303–304.
Gaggioli, The use of force in armed conflict (n 132) p. 468.
The commonalities of national self-defence rules are summarised differently by different experts. Fletcher claims that most legal systems share four common characteristic: imminence, necessity, proportionality and the intention to repel an attack. Fletcher, Basic Concepts of Criminal Law (n 117) p. 133. Ohlin argues there are three generally recognised criteria: imminence, proportionality and unlawfulness. Ohlin, ‘Self-defence’ (n 231) p. 507.