Given the rapid rise in space activities in recent years, it is striking that there has been no corresponding change or addition to the core space law treaties since they were adopted in the 1960s and 1970s. There have also been very few cases before courts, whether international, regional, or domestic, in which the provisions and principles of space law have been authoritatively interpreted or applied.1 As a result, the legal approach to establishing State accountability for space pollution is not particularly settled.2 When it comes to nsas, the legal framework is even more embryonic.3 Because of this, it is particularly important to examine the legal regimes potentially relevant to nsa accountability for space pollution.4 In order to do so, it is necessary to address the fundamental prefatory question of whether there is a prohibition of space pollution under international law.
1 The Quest to Discern a Prohibition of Space Pollution
1.1 Does International Space Law Prohibit Space Pollution?
The presence of debris in outer space should be considered a form of environmental degradation on a global scale.5
As noted above, the nucleus of international space law8 is made up of several conventions, namely the 1967 Outer Space Treaty, the 1968 Rescue Agreement, the 1972 Liability Convention, the 1975 Registration Convention, and the 1979 Moon Agreement, along with the 1963 Partial Test Ban Treaty. Soft law instruments provide additional interpretive aides and sources of guidance. These instruments constitute the core body of legal provisions to explore in the effort to determine whether a prohibition of space pollution exists.
Widely recognized as the ‘constitution’ of international space law,9 the Outer Space Treaty of 1967 is the most authoritative instrument from which a prohibition of space pollution could be derived. The Outer Space Treaty is a fundamental instrument regulating human activities in outer space, which has attracted broad acceptance in the international community.10
Outer space, including the moon and other celestial bodies, shall be free for exploration and use by all States without discrimination of any kind, on a basis of equality and in accordance with international law, and there shall be free access to all areas of celestial bodies.
The Preamble to the Outer Space Treaty contains similar language. However, Article i(2) could also be read in a more environmentally protective way, namely, to mean that all space activities must be carried out with a view to ensuring that space remains free to access for future expeditions and activities. In this manner, it would require actors engaged in space activities to pay due heed to the environmental impact of their endeavours. That would be consistent with the context of the Outer Space Treaty, including Article ix. It would prioritize an effet utile interpretation in light of the object and purpose of the Outer Space Treaty, which is also evolving12 in light of the modern situation of increasing numbers of satellites and space objects clogging up access to space and risking collisions and the exponential increase of space debris.13 The core purpose of the Outer Space Treaty focuses on ensuring that the exploration and use of outer space remains the ‘province of all mankind’. This could be significantly undermined if space becomes overcrowded with non-operational pieces of junk hurtling around at astronomic speeds, as access to space will become increasingly difficult and expensive, putting it out of reach of the vast majority of States, people, and organisations throughout the world.
In the exploration and use of outer space, including the moon and other celestial bodies, States Parties to the Treaty shall be guided by the principle of co-operation and mutual assistance and shall conduct all their activities in outer space, including the moon and other celestial bodies, with due regard to the corresponding interests of all other States Parties to the Treaty. States Parties to the Treaty shall pursue studies of outer space, including the moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose. If a State Party to the Treaty has reason to believe that an activity or experiment planned by it or its nationals in outer space, including the moon and other celestial bodies, would cause potentially harmful interference with activities of other States Parties in the peaceful exploration and use of outer space, including the moon and other celestial bodies, it shall undertake appropriate international consultations before proceeding with any such activity or experiment. A State Party to the Treaty which has reason to believe that an activity or experiment planned by another State Party in outer space, including the moon and other celestial bodies, would cause potentially harmful interference with activities in the peaceful exploration and use of outer space, including the moon and other celestial bodies, may request consultation concerning the activity or experiment.16
Article ix does not explicitly refer to space pollution or debris. Indeed, the Outer Space Treaty was ‘negotiated and established before debris was recognized as a problem’.17 Nonetheless, Article ix does prohibit ‘harmful contamination’, which are the key words on which a prohibition of space pollution can be based.18
inactive payloads (former payloads which can no longer be controlled by their operators), operational debris (objects associated with space activities, remaining in outer space), fragmentation debris (products of explosions and collisions) and microparticulate matter (a catch-all category including micro-sized objects, such as solid-propellant rocket motor effluent, paint flakes and thermal coatings, and spacecraft-induced phenomena such as outgassing of heavy molecules and space glow).21
Negotiators of the Outer Space Treaty considered that the treaty’s prime objective was the effective utilization of outer space. Given that view, it could be argued that any environmental protection provided by the Outer Space Treaty would merely be a ‘fortuitous by-product’.22 Reportedly, the US ‘West Ford Experiment’ (a military experiment in the 1960s in which millions of copper dipoles were placed in orbit in an attempt to allow long distance communications by bouncing radio waves off them) prompted the ‘harmful contamination’ formulation of Article ix.23 Because of fears of cutting off access to space, the wording of Article ix stresses the obligation to pay due regard to
Nonetheless, the fact that Article ix uses the word ‘contamination’ signals a bifurcated scope of protection. It encompasses both the prohibition of harm to the outer space environment (and backwards contamination of Earth) and the obligation for States to avoid restricting others’ access to outer space, which they enact through measures such as consultation when their activities or experiments could interfere with other State Parties’ space operations. Encompassed within the obligation to pay ‘due regard’ is the responsibility to ‘avoid creating hazards that could adversely affect the safe conduct of space activities by other states’, such as space pollution.25 Moreover, access to space and space pollution are inherently interconnected. As set out above, if the current production of space debris continues unchecked, then the freedom to use and explore outer space (the main objective of the Outer Space Treaty)26 will be rendered extremely dangerous and difficult, if not impossible.27 By guaranteeing free exploration and use, the Outer Space Treaty places the same obligation on States to keep outer space in a condition that permits free exploration and use, in line with the object and purpose of this treaty.28
Bearing in mind the range of opinions on the interpretation of Article ix of the Outer Space Treaty, it is nonetheless clear that pollution in space would constitute ‘harmful contamination’, so long as more than merely de minimis or negligible.29
Another textual feature of this provision is that Article ix refers explicitly to avoiding harmful contamination in ‘studies’ and ‘the exploration’ of outer space, but does not explicitly extend this prohibition to its ‘use’.32 Space pollution often arises from activities such as launching satellites and sending testing equipment to the moon or Mars, which do not necessarily constitute ‘exploration’ in the sense of searching for new unexplored areas. For commercial activities by nsas in particular, the label of exploration will often not be the most fitting. Profit-seeking companies will instead look to exploit outer space and celestial bodies to generate income. Given that those activities will raise risks of accidental or purposeful creation of space debris, this interpretive issue is of potential future consequence for any legal proceedings based thereon. It places a significant doubt over the utility of Article ix to found a prohibition against space pollution.
In light of the context, object and purpose of the Outer Space Treaty, the term ‘exploration’ in Article ix can be interpreted in a broad manner, to encompass activities in general.33 That interpretation is available on the basis of the text alone. Activities in space have traditionally been referred to with the language of exploration, as immortalized in the phrase ‘space, the final frontier’.
However, an argument could be made that this broad reading of ‘exploration’ would clash with the other terms of the Outer Space Treaty, as provisions such as Article vi refer to ‘activities’ in space. If the drafters had wanted ‘exploration’ to cover all space activities they could have used that wider term. Nonetheless, the context signals that a broad reading of the terms ‘studies’ and ‘exploration’ should be preferred; the second sentence of Article ix adds to the due regard principle in the first sentence, which covers all activities in space, and the context does not provide a strong indication that it was meant to be restricted to the mapping out of space for its discovery, and instead was meant to encompass a range of human activities in space.35
There is a further question regarding the requirement that State Parties ‘shall adopt appropriate measures for this purpose [avoiding harmful contamination]’.36 The term ‘appropriate’ is a wide and malleable one, which could invite self-serving interpretations by States looking to minimize their responsibility and maximize their range of maneuver. However, an interpretation in line with the effet utile approach would see the term ‘appropriate’ given an objective meaning – namely the proportionate measures objectively required to address the harm, rather than what a State claims it subjectively considered appropriate in the circumstances.
Additionally, Article ix imposes an obligation on State Parties to adhere to the principle of cooperation and mutual assistance when conducting exploration and use of outer space. This expands on the direct obligation to avoid harmful contamination and provides a strong basis to read Article ix as requiring States to communicate and coordinate when a risk of harmful contamination arises.37 Additionally, the 1968 Rescue Agreement, the 1972 Liability Convention, and the 1975 Registration Convention provide useful tools for regulating international cooperation during space activities, which will be useful
Complimentary to Article ix are Articles i and ii of the Outer Space Treaty, which specify that exploration and use of outer space shall be free to all States and shall be the province of all mankind. Importantly, Article ii provides that ‘[o]uter space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.’ These two provisions together designate outer space as res communis.38 In this way, the outer space environment, including on celestial bodies, can be seen as protected by existing space law insofar as its protection is necessary to ensure humankind’s access to as well as the use and exploration of outer space.39 Although causing space pollution, such as through space debris, would not naturally constitute appropriation, the broader message of protecting the accessibility of space and avoiding its cluttering with anthropogenic matter is consistent with the approaches taken above.40
Separately, Article iv, forbids the stationing of ‘any objects carrying nuclear weapons or any other kinds of weapons of mass destruction’ in outer space and provides that the Moon and other celestial bodies are reserved for ‘exclusively peaceful purposes’, thereby banning all military activity on celestial bodies at least. By prohibiting a major potential source of pollution, Article iv provides a measure of indirect protection for the space environment. However, the prohibition centres on the weapons per se, and any benefits for the space environment are only incidental to that aim.
In addition to the Outer Space Treaty, the Moon Agreement has potentially relevant provisions concerning a prohibition of space pollution, including
These provisions are consistent with an interpretation of space law which precludes space pollution. In this light, the Moon Agreement has been described as ‘the most advanced of the space treaties in an environmental sense.’42 Indeed, its protections are formulated in a broader and more concrete way in comparison to the Outer Space Treaty. However, the Moon Agreement (likewise) does not have any sanctions provisions.43 Moreover, due to its low ratification status, the Moon Agreement is currently of limited legal weight.44 It had only 17 ratifications as of January 2024, with leading space-faring countries not among them. Nonetheless, it entered into force in July 1984 when Austria became the fifth State to ratify the Agreement.
Beyond the Outer Space Treaty and the Moon Agreement, there is the Liability Convention. Article xxi of the Liability Convention refers to damage caused by space objects constituting ‘a large-scale danger to human life’ or threatening to seriously interfere with ‘the living conditions of the population or the functioning of vital centres’. These terms could cover environmental destruction, whether anthropocentric or due to natural disasters.45 However, the interpretation is not beyond debate, and its reference to ‘damage’ could also be seen as related primarily to matters of harm to anthropogenic objects or possessions. Indeed, Articles iii and iv of the Liability Convention indicate that the damage has to be inflicted on the space object of a launching State, or persons or objects aboard, (unless it occurs on the surface of the Earth).46
Amongst the other international space law treaties, there is little that could be construed as a direct prohibition of space pollution. The 1963 Partial (Nuclear) Test Ban Treaty is the most relevant, as it removes a major source of potential space pollution by banning nuclear tests in the atmosphere. However, it is focused on the nuclear explosion rather than environmental pollution per se, and only provides incidental protection for the space environment.
When interpreting the Outer Space Treaty and other international treaties, it is useful to look at subsequent agreements, soft law, and domestic laws, which provide context for the interpretation of the articles of the Outer Space Treaty.48 As detailed in Chapter 5, Germany, United States, Canada and the Russian Federation, for example, have explicit national policies focused on mitigation of space debris.49 Similarly, the European Space Agency (esa) ‘Space Debris Mitigation Policy for Agency Projects’ generally requires all esa projects to limit space pollution.50 Another example is provided by international standards, like the iso Standards,51 and Radiocommunication Sector of the International Telecommunication Union (itu), Recommendation on the ‘Environmental Protection of the Geostationary-Satellite Orbit’ of 2004, and the iadc and uncopuos sdmg.52 These instruments essentially aim
UN General Assembly (unga) declarations or recommendations56 concerning national legislation relevant to the peaceful exploration and use of outer space can be indicative of the subsequent interpretation of hard law obligations. Importantly, States’ contributions to these instruments can also provide evidence of opinio juris57 and potentially State practice,58 which are the building blocks of customary international law. Adopted without a negative vote, in 2013 the UN General Assembly noted in Resolution 68/74 the ‘need to maintain
From these materials, it can be concluded that space law prohibits the pollution of the outer space environment. However, that claim is not beyond dispute, as the relevant provisions and instruments are not as explicit and definitive as well-established interdicts under international law.62 The leading provision of international space law remains Article ix of the Outer Space Treaty. Its reference to ‘harmful contamination’ can encompass anthropogenic pollution in space which meets the threshold of ‘harm’. UN issuances, such as Resolution 68/74 support the conclusion that space pollution is prohibited. Nonetheless, the genesis of Article ix of the Outer Space Treaty and the lack of consistent State practice condemning space pollution means that the extent of the conventional basis for a prohibition of space pollution will continue to be contested as long as it is not explicitly spelt out in an international convention.
In this light, it is apposite to look beyond international space law and survey international environmental law to discern whether and how it further supports a prohibition against space pollution under international law.
1.2 Does International Environmental Law Prohibit Space Pollution?
Having examined whether a prohibition of causing space pollution can be found in space law, the survey now expands to address whether causing harmful pollution in space would violate existing principles of international environmental law. Although the Outer Space Treaty was negotiated before a majority of the environmental law instruments were adopted, Article iii of the Outer Space Treaty provides that State Parties involved in the exploration and
Because Article iii ensures that the Outer Space Treaty framework is not a hermetically-sealed ‘self-contained regime’,65 it should be interpreted in line with, and as complemented by, international law. Accordingly, rules of general international law, including customary international law particularly customary international environmental law,66 can be used to interpret the meaning of
it is without any doubt that a substantial part of international law and the UN Charter apply to human activities in outer space. Furthermore, [through] [A]rticle iii, developments in international law, such as new international agreements, rules of customary law or new interpretations of the provisions of the UN Charter, which are compatible with the peculiarity of the space activities, can be extended to the use of outer space.68
The phrase ‘in accordance with’ in Article iii provides a basis to interpret the Outer Space Treaty’s consistently with international law more broadly.69 Further, it also potentially permits other principles and facets of international law to be read into the treaty, to complement the provisions of the Outer Space Treaty.70 This later reading of Article iii would build on the interpretive approach of systemic integration of international space law with other branches of international law.71 However, that reading, which would effectively incorporate by reference general international law into the Treaty’s framework,
The most dynamic source of international law that may apply to activities in outer space is that of customary international law.74 Customary international law imports a broad array of principles and rules to complement the provisions of the Outer Space Treaty framework.75 Breccia argues that several key principles of international environmental law are relevant to space activities, namely ‘prevention and precaution’, ‘environmental impact assessments’, ‘access to information’, ‘participation in the decision-making process’, and ‘common but differentiated responsibilities’.76 He acknowledges that one cannot begin with the assumption that all environmental principles are ‘indiscriminately’ applicable to space activities and instead asserts that that it is necessary to assess the environmental principles’ applicability from both a technical-scientific standpoint and from a strictly legal perspective, and to discern whether any of the principles need adaption to apply in the space environment.77 Accordingly,
To assess the applicability of customary international environmental law, it is necessary to know whether outer space qualifies as part of the ‘natural environment’. However, there are multiple definitions of the term ‘natural environment’, some of which do not cover outer space. Whereas the International Law Commission (ilc) appears to limit its enumerated definition to the earth, seas and the atmosphere (and elements therein), it does allow for the natural environment to extend to ‘where the human race develops’.78 The Partial or Limited Nuclear Test Ban Treaty lists outer space as ‘man’s environment’.79 The United Nations body uncopuos reports routinely refer to the ‘space environment’,80 and several other organizations refer routinely to the ‘space environment’.81 The Council of Europe included outer space in its definition of the ‘human environment’.82 Moreover, in 2021, an Independent Expert Panel released a definition of ecocide for consideration by the States Parties to the icc in which it defined the environment to mean ‘the earth, its biosphere,
In light of the multiple ways in which outer space can be included in the definition of the ‘natural environment’, this article proceeds on the basis that outer space can be encompassed by that term and that international environmental law principles are potentially applicable to outer space pursuant to Article iii of the Outer Space Treaty. At the same time, these international environmental law principles must be applied subject to any necessary adjustments in light of the differing considerations arising from the terrestrial and spatial settings.
With those preliminary issues addressed, there are several established principles of international environmental law which could impact on the prohibition of space pollution. The following environmental principles are those considered to have the greatest potential application to human activities in outer space.
1.2.1 No-Harm Principle
Of primary importance to space pollution is the ‘no harm’ principle.86 This was famously set down in the Trail Smelter
Under the ‘no harm’ principle, States must ensure that activities within their jurisdiction do not cause significant environmental damage outside their jurisdiction.91 The International Court of Justice has confirmed that, under this international obligation, States must ensure that activities within their jurisdiction and control respect the environment of other States or of areas beyond national control.92 The ‘no harm’ principle is violated when the damage reaches the threshold of significant harm, as determined by the International Law Commission in its Draft Articles on the Prevention of Transboundary Harm from Hazardous Activities.93 In this regard, harm encompasses ‘harm caused to persons, property or the environment’.94 The term
There is a relatively direct line of argument to show that the causation of space pollution would constitute a violation of the international environmental law ‘no-harm’ principle. Schellekens argues that causing space debris constitutes a violation of the no-harm principle.97 According to Dennerly, the no-harm threshold would appear to be met, as he argues that ‘space activities, such as the operation of space objects, that encompass the potential to create space debris in orbit is considered ultra-hazardous for the purposes of the Articles on Transboundary Harm.’98 Similarly, Stubbe concludes that ‘there can be no doubt that debris pollution in outer space is of a transboundary nature because it occurs in a res communis area beyond national jurisdiction’ and that space debris can qualify as ‘any detrimental change to the environment [including outer space]’.99 Given the risk of exponential harm deriving from ever fragmenting items of space debris, and the looming Kessler effect, the risk engendered by even a small amount of space debris is greater than the immediate harm it can cause to another space object, and should be considered significant in most, if not all, instances.100
Regarding the obligations that arise from the no-harm principle, in the case concerning Pulp Mills on the River Uruguay (Argentina v. Uruguay) the
However, in practice, the requirement to exercise due diligence, typically in the form of an environmental impact assessment, is not exhaustively complied with. Several states require an environmental impact assessment within their national space authorization procedures and national space laws.104 But the assessments are mainly directed at impact on the terrestrial environment, and it is unclear whether they are consistently adhered to even in States where they are required.105
Consequently, there is a strong basis to assert that the no-harm principle should apply to outer space, as it constitutes an area beyond national jurisdiction and the environment is generally interpreted to encompass outer space. Significant harm must be shown at minimum to trigger the application of this principle to a specific case. While a violation of due diligence obligations may demonstrate a violation of this principle, the support for the enforceability of such obligations is somewhat undermined by the lack of universal adherence to this duty in State practice.106
1.2.2 Precautionary Principle
The precautionary principle, which is recognised in Principle 15 of the 1992 Rio Declaration, provides that ‘where there are threats of serious or irreversible environmental damage, a lack of full scientific certainty shall not be used
the Precautionary Principle would require a launching state as well as a non-governmental operator to take extra precaution in launching a space object that may result in space debris. Such a precaution would,
at a minimum, require a state and an operator to observe the Space Debris Mitigation Guidelines, which are founded on normal operating procedures.110
This approach would require reading Article ix’s prohibition of harmful contamination as incorporating a precautionary facet. While it is important that States do not use the absence of scientific certainty to avoid taking precautionary measures, the question arises how this principle would be applied in the space sector as a legal doctrine.
One manifestation of environmental law related to the precautionary principle is the requirement to conduct environmental impact assessments. This reflects the reasonable regard due to the rights of other States.111 Environmental assessments have been incorporated into some national space legislation in multiple countries including Belgium and the United Arab Emirates.112 However, to date these have largely focused on the impact of space activities on the earthly environment.113 Beyond this, the precautionary principle can be read into several other principles of space law, including for establishing liability for harm caused in space,114 as well associated with soft law instruments such the space debris mitigation guidelines.115 In this way, the failure to take precautions would not itself constitute a violation of the prohibition of space pollution but would constitute an ancillary and complementary protection of the outer space environment.
Despite this grounding in customary international law, there is currently no legal instrument that would explicitly decree the observance of the
1.2.3 Principle of Sustainable Development
The principle of sustainable development is a core environmental tenet, which features in several principles of the 1972 Stockholm Declaration,117 in at least 12 of the Rio Principles of 1992,118 along with several international treaties,119 soft law instruments120 and national acts.121 It was first authoritatively described in the epoch defining Brundtland report as ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’.122
Throughout the ages, mankind has, for economic and other reasons, constantly interfered with nature. In the past, this was often done without consideration of the effects upon the environment. Owing to new scientific insights and to a growing awareness of the risks for mankind – for present and future generations – of pursuit of such interventions at an unconsidered and unabated pace, new norms and standards have
been developed, set forth in a great number of instruments during the last two decades. Such new norms have to be taken into consideration, and such new standards given proper weight, not only when States contemplate new activities but also when continuing which activities begun in the past. This need to reconcile economic development with protection of the environment is aptly expressed in the concept of sustainable development.123
Sustainable development has three facets – environmental, economic and social. The goal is consequently ‘to balance environmental protection and economic development in a way that is sustainable for both present generations and the future of humankind.’124 In this respect, it is closely linked to the principle of intergenerational equity, which is addressed below.125
The basic goal of the principle is to balance environmental protection and economic growth in a sustainable manner. In practice this has been explained as ensuring environmental concerns are considered when developing developmental policy, whereby the environment is treated as a resource and sustainable is taken to mean ‘non-exhaustive’.126 In other words, development and growth should be achieved in a manner that does not exhaust the natural resources available.127 As such, for the principle of sustainable development, the environment itself is not the primary core protected value, but its protection is the by-product of promoting human welfare,128 as humans inherently live within nature and thus depend on it.129
In the field of space law, sustainable development therefore has particular resonance. Modern life has become heavily dependent on satellite services.130 Space-based satellites form an integral part of the proposed means to ensure
Considering that copious amounts of space debris already orbit the Earth, ensuring the continued sustainability of utilizing outer space will be a key challenge confronting humanity. For this reason, Breccia notes that ‘the principle of sustainable development is acquiring relevance even in the space sector’.132 This is demonstrated aptly by yearly uncopuos Subcommittee meetings, which include space sustainability as a regular item on the agenda. It is also shown by the Long-Term Sustainability Guidelines, and the uncopuos Space Sustainability Working Group,133 as well as by various initiatives levied to achieve space sustainability.
However, the justiciability of the concept of sustainable development is disputed.134 Specifically, because it is so broad-ranging, it would pose challenges to courts to enforce. Institutions in which environmental damage could be prosecuted are unlikely to have provisions imposing criminal sanctions for
1.2.4 Principle of Intergenerational Equity
The principle of intergenerational equity holds that resources should not be used by current generations in such a way that it will prejudice future generations’ access to those resources.137 It is intertwined with the principle of sustainable development outlined above. Non-renewable resources are particularly important concerns for this principle, as equity demands that they are not exhausted or overly dissipated by current generations to the prejudice of succeeding ones.
In relation to space activities, this principle has a clear basis of applicability.138 In addition to non-renewal resources such as minerals on celestial bodies, Goh observes that
some space resources, while undepletable, are limited. The radio spectrum on which all space communication depends and the geostationary orbit on which most communication satellites are deployed are examples of these limited resources. These have to be equitably shared.139
As noted above, this has been more clearly formulated in the fifth space treaty, the Moon Agreement. Article 4 provides that the exploration and use
Space has been described as an environment shared by all States, populations and generations.143 It has been observed that the current exponential increase of space launches and space objects risks depriving future generations of fair opportunities to explore and utilize space. Radi states that ‘[t]his would create a fundamental intergenerational inequity by depriving – partly or fully – future generations of the enjoyment of the most fundamental space right: the right to explore and use space freely.’144
Breccia argues that the principle of intergenerational equity applies to outer space activities as it can be found in Article i of the Outer Space Treaty implicitly.145 By decreeing that outer space shall be free to be explored and used by all
A practical facet of the equitable principle is that the limited resources of outer space, such as geostationary orbital positions, should be shared equitably among countries. This is set out in the 2007 uncopuos report.147 Although it is focused on the division of benefits at the present time, it will also have an impact on future generations as they will be impacted by the level of equity achieved in sharing out these orbital positions. If they are deprived of such opportunities at present, then the situation will only become more entrenched and inequitable as time marches on and future generations arrive.
In essence, the principle of intergenerational equity suffers from the same strengths and weaknesses as the principle of sustainable development. In the space domain it is strongly heralded by developing States, who are currently unable to partake in space activities and therefore wish to ensure that they will have this opportunity in the future. However, its practical application is less commonly discussed and so it remains unclear how it could impact on the use of international law to redress space pollution.
1.2.5 Principle of Common-but-Differentiated Responsibilities
According to the principle of common-but-differentiated responsibilities those States which have historically created more pollution bear a higher responsibility to mitigate the damage to the environment.148 This has emerged as a key principle supported by many in the Global South, particularly in the context of combating climate change. In accordance with this approach, international law instruments often differentiate, at least in some manner, between industrialized and developing States.149 Whilst the Outer Space Treaty does not explicitly contain this principle, it does provide that space exploration and use should be carried out for the benefit of all countries irrespective of their economic development. The rationale for this is two-fold; first, is that
There is a basis in space law to incorporate the principle of common-but-differentiated responsibilities. The Principles Governing The Use By States Of Artificial Earth Satellites For International Direct Television Broadcasting contained in the Annex to unga Resolution 37/92 of 1982, provide in Paragraph 2 that ‘[s]uch activities should promote the free dissemination and mutual exchange of information and knowledge in cultural and scientific fields, assist in educational, social and economic development, particularly in the developing countries, enhance the qualities of life of all peoples and provide recreation with due respect to the political and cultural integrity of States.’152 Similarly, Paragraph 11 provides that, in cooperating on the protection of copyright and related rights, States ‘should give special consideration to the interests of developing countries in the use of direct television broadcasting for the purpose of accelerating their national development’.
Against this background, it should be noted that the impact of the recognition of the common-but-differentiated responsibilities in space law on a putative prohibition of space pollution is distributive rather than prohibitive. It does not constitute a basis for banning space pollution per se. Nonetheless, it would potentially affect the levels of chemical emissions and other pollutants in space which would be justifiable depending on the launching State in question (more developed States would be expected to have the highest environmental protections and therefore the lowest emissions).
Relatedly, common-but-differentiated responsibilities imply a responsibility on the part of developed States to assist developing States. This would be relevant to space remediation efforts to clear space debris for example. A basis for this can be seen by analogy in the 1986 unga Resolution 41/65 on the ‘Principles Relating to Remote Sensing of the Earth from Outer Space’ which provides in Principle ii that ‘[r]emote sensing activities shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic, social or scientific and technological development, and taking
Similarly, the United Nations Declaration on International Cooperation in the Exploitation and Use of Outer Space for the Benefit and in the Interest of All States, Taking into Particular Account the Needs of Developing Countries was adopted by the United Nations General Assembly in its Resolution 51/22 of 13 December 1996. Although Resolution 51/22 is ‘soft law’, it can be used as a significant source to impact the interpretation of provisions of ‘hard’ space law, particularly as it is directly relevant to Article i(1) of the Outer Space Treaty.154 Again, these principles would be primarily relevant to space environment remediation efforts rather than the prohibition of space pollution per se.
The principle of common-but-differentiated responsibilities has been adopted in multiple environmental law instruments in order to better achieve environmental policies across all States, particularly in the global South.155 However, this principle is not without dangers, as many industries or nsas could effect a transfer to developing states in order to undertake environmentally degrading activities for higher gain, thus actually increasing environmental degradation.156 To counter this it is necessary to stress that common-but-differentiated responsibilities measures must be temporary in nature and only designed to apply as long as the developing State is at significant disadvantage in its ability to engage in relevant activity.157
Two differentiating views can be found in doctrine regarding the applicability of the common-but-differentiated responsibilities principle to outer space
The second view, relying on Article iii of the Outer Space Treaty, claims that it is through that Article that the common-but-differentiated responsibilities principle applies to outer space, and that such interpretation is in line with Article i of the Outer Space Treaty.161 It could be operationalized by assigning different obligations to States at different levels of economic development, while also encouraging the sharing of knowledge to advance all States’ knowledge and advancement.162
Generally, industrialized States, which have the desire and existing capacity to engage in space activities, will be more likely to pollute the environment and are therefore pushing back against any blanket prohibition of space pollution.163 This is not to say these are opposed to action being taken to protect the space environment. To the contrary, space faring nations are highly concerned about the space environment and the connected access to space.164 These protections are, however, in essence directed at all parties already partaking in space activities, thus not in line particularly with common-but-differentiated
As noted, according to the common-but-differentiated responsibilities principle, a greater responsibility for the maintenance of the environment should be assigned to the space powers that have carried out majority launches in the past.167 However nowadays, more and more launches are conducted by nsas. By extending the ratio of the principle of common-but-differentiated responsibilities to apply to nsas, one could argue that nsas that cause the most space pollution carry more responsibility to mitigate it. It is not evident that any such trend is materializing in practice. Nevertheless, common-but-differentiated responsibilities could be used in this manner to require nsas to engage in remediation efforts, particularly nsas from developed States. Another proposal has been that of a fund for space activities, to provide a ready means of facilitating common-but-differentiated responsibilities, as well as other principles such as the polluter-pays or inter-generational equity ones.168 But this is a prospective financial measure rather than a legal adjustment to impose accountability for space pollution.
1.2.6 Polluter-Pays Principle
Another important customary international environmental rule is the polluter-pays principle ascribing liability for damages to the polluter.169 The principle was first introduced by the Organization for Economic Co-operation and Development in 1972 and can furthermore be found, for example, in Article 16 of the Rio Declaration.170 According to this principle, where harm arises to any facet of the environment, it is the person or entity which caused the harm which should pay for the full remediation of that environmental harm. It
The applicability of this principle to outer space activities, however, remains disputed. The principle was initially designed for terrestrial activities, and the closest rule in space law to it is the concept of liability for damages caused by space objects, even though the damage defined in Liability Convention does not explicitly cover environmental damage. In the terrestrial context, proportionality between pollution and demanded compensation are easier to define and lower than in the space sector, where the expenses of activities are extremely high even without compensation for the pollution, and establishing proportionality is a more novel field.172 There is likely little doubt that application of the polluter-pays principle would help deter the proliferation of space debris, however, at present the principle is not being applied in practice to space activities. Moreover, it would not contribute to showing a violation of the prohibition of space pollution but instead assist the determination of where responsibility and liability should fall in cases of harm to the outer space environment.
1.2.7 The Principle of Permanent Sovereignty over Natural Resources
The principle of permanent sovereignty over natural resources seeks to establish a right of ‘governments to exploit the State’s natural resources on behalf of the State and its people on condition that it does so for national development and the well-being of the people of the State.’173 Its foundational document is the 1962 General Assembly Resolution 1803 on Permanent Sovereignty over Natural Resources, which recognizes that ‘respect [for this principle] must be based on the recognition of the inalienable right of all States freely to dispose of their natural wealth and resources in accordance with their national interests, and on respect for the economic independence of States’.174 In relation to space law, the 1986 Resolution 41/65 of the United National General Assembly (‘Principles Relating to Remote Sensing of the Earth from Outer Space’), makes
Given that outer space, including the Moon and other celestial bodies, is not subject to national appropriation whether by claim of sovereignty of otherwise,175 the principle of permanent sovereignty over natural resources should not have application in this environment. However, space exploration can involve the exploitation of natural resources on earth, such as rare metals and compounds. To the extent these natural resources are exploited for the construction of space objects or for their launch, those natural resources should be utilized with respect for the principle of disposing of wealth in the interests of the peoples of the relevant State in question.
1.2.8 Other Bases under International Environmental Law to Prohibit Space Pollution
Among key international environmental law instruments, several accord the environment intrinsic value. Of greatest general import is the 1992 Convention on Biological Diversity, which is motivated by the ‘the intrinsic value of biological diversity’ and ‘the importance of biological diversity for evolution and for maintaining life sustaining systems of the biosphere’, while also noting ‘the ecological, genetic, social, economic, scientific, educational, cultural, recreational and aesthetic values of biological diversity and its components’.176 Moreover, the 1972 World Heritage Convention defines natural heritage as natural features, geological and physiographical formations, and natural sites of ‘outstanding universal view’ from the ‘point of view of science’ and ‘conservation’, as well as due to aesthetic value.177 To date, the application of these instruments has been limited to terrestrial environments, and it remains unclear whether and how they could be applied to the context of outer space. Von der Dunk argues that outer space constitutes a ‘global commons’, and he specifies that this has different legal implications from a ‘common heritage of mankind’ designation. Whereas the former protects the fundamental freedom to act except to the extent that specific obligations have been agreed to the contrary, the latter establishes a presumption against any exploitation of
Another potential source of a prohibition of space pollution is the Convention on the Prohibition of Military and Other Hostile Use of Environmental Modifications (enmod). Adopted in 1977, this treaty was essentially a reaction to events during the Vietnam War, including the use of high quantities of chemical defoliants against large tracts of forest, by the United States Army, which resulted in significant destruction of forests and wildlife as well as high levels of human ill-health and death.181 In its Article ii, it provides that ‘the term ‘environmental modification techniques’ refers to any technique for changing – through the deliberate manipulation of natural processes – the dynamics, composition or structure of the earth, including its biota, lithosphere, hydrosphere and atmosphere, or of outer space.’182 It prohibits State Parties from engaging in ‘military or any other hostile use of environmental modification techniques having widespread, long-lasting or severe effects as the means of destruction, damage or injury to any other State Party.’
Military uses of outer space are increasingly being researched by States and other entities. Because of the nature of outer space, and the lack of gravity or atmospheric friction, the spreading of space debris through military activities, collisions or other activities is likely to be long-lasting unless specifically
1.2.9 Conclusion on International Environmental Law
There is considerable overlap between several of the environmental law principles discussed above, particularly when it comes to space law. However, for present purposes it is striking they all have the common element of not having been applied in legal cases on the space environment. While the principles such as no-harm, prevention, precaution, polluter-pays, intergenerational equity, common-but-differentiated responsibilities, conducting environmental impact assessments and access to information are ‘cornerstones of international environmental law’,184 they cannot be ‘indiscriminately’ transposed to the context of outer space, but instead must be assessed from technical-scientific and legal points of view.185 Moreover, the status and content of the majority of international environmental law principles mentioned in this chapter remain open to debate, particularly when applied to outer space. They permit various interpretations and therefore make it difficult to establish specific obligations for application in legal settings such as courts. This is because they are principles, formulated vaguely and thus suffering from the same issue plaguing the Outer Space Treaty in this regard. On the other hand, as Lyall and Larsen point out, ‘[i]t would be wrong to consider the law of space environment as something separate, distinct and different from the concepts
The ambiguity and vagueness of international environmental law limits the legal applicability of its specific principles. This, coupled with the fact that international environmental law treaties and principles were designed with terrestrial environment in mind, lead to it providing few clear instructions for States’ activities in space. As such, environmental law principles may help guide the development and interpretation of space law from an ecocentric perspective, but at present remain insufficient on their own to indisputably demonstrate a prohibition of space pollution.
[a]s space exploration expands further into outer space and takes more extensive forms, such as construction of permanent facilities and the utilization of natural resources for the support of missions, anthropogenic alterations of this environment and the related hazards will be of an order of magnitude far greater than those seen today.188
This augurs in favour of a re-orientation in space law towards more ecocentric inclusivity. Such a shift would not mean removing the opportunity for space exploration or utilization by humans, but rather adopting a viewpoint prioritizing the protection of outer space as a fundamental starting point among the values to weigh when adopting or amending the international legal framework governing space activities.
1.3 The Relevance of the Human Right to a Clean, Healthy and Sustainable Environment
An alternative legal regime that has recently been growing in relevance to environmental harm is that of international human rights law. Although there are several human rights which may be affected by events in space, the present analysis focuses on those human rights intertwined with harm to the environment. In this respect, the most notable potential human right is that to a clean, healthy and sustainable environment, recognised in 2022 by the United Nations General Assembly.189 Notably, Resolution 76/300 had 161 votes in favour, eight abstentions, and no votes against. This followed similar recognition by the Human Rights Council in 2021 and within the inter-American system of human rights.190
Concerning the potential application of this right to the outer space environment, there is little guidance provided in the implementing resolution. The United Nations General Assembly notes ‘that the right to a clean, healthy and sustainable environment is related to other rights and existing international law’ and affirms ‘that the promotion of the human right to a clean, healthy and sustainable environment requires the full implementation of the multilateral environmental agreements under the principles of international environmental law’.191 At the same time, this language leaves open the question of whether the environment would include outer space. In recognizing the same right, the Inter-American Court of Human Rights has held that it ‘protects the components of the environment, such as forests, seas, rivers, and other [environmental features] as legal interests in themselves, even in the absence of certainty or evidence of a risk to individuals’ and that ‘[t]his means that nature must be protected, not only because of its benefits or effects for humanity, ‘but because of its importance for the other living organisms with which we share
International human rights law is increasingly being used to litigate environmental concerns, including before the European Court of Human Rights and the Inter-American Court on Human Rights.195 In addition to the right to a clean, healthy and sustainable environment, there are several pre-existing human rights that have been found to undergird the right to a healthy environment, which was recently recognised by the hrc among other notable bodies.196 Chief among these rights are the right to life and the right to private and family life.197 These rights have been found to have been violated by environmental harm on Earth, but remain untested in this respect in the context
Applying human rights in the outer space context can draw lessons from climate change litigation before human rights bodies. For example, in the recent case of KlimaSeniorinnen, the ECtHR addressed the risks to elder Swiss citizens produced by climate change. It noted that it is not sufficient it for an applicant to complain of general damage to the environment.199 Instead it looked at criteria such as the ‘minimum level of severity of the harm in question, its duration and the existence of a sufficient link with the applicant or applicants, including, in some instances, the geographical proximity between the applicant and the impugned environmental harm.’200
When it came to assessing responsibility for related human rights violations, it held that, although ‘climate change is undoubtedly a global phenomenon which should be addressed at the global level by the community of States’, it remains the case that ‘each State has its own share of responsibilities’ and that ‘a respondent State should not evade its responsibility by pointing to the responsibility of other States’.201 On a related point concerning the ‘drop-in-the-ocean’ argument, the Court recalled that ‘sufficient to engage the responsibility
Ultimately, the Court found Switzerland to have violated its obligations under Article 8 concerning private and family life (which it saw as ‘encompassing a right for individuals to effective protection by the State authorities from serious adverse effects of climate change on their life, health, well-being and quality of life’), as well as access to justice, but only in relation to the association and not in relation to the individual victims.204 Specifically, it pointed to ‘critical lacunae in the Swiss authorities’ process of putting in place the relevant domestic regulatory framework, including a failure by them to quantify, through a carbon budget or otherwise, national green-house gas emissions limitations.’205
When applied to the space context, these findings suggest two potential points of applicability. First, in relation to State responsibility (and potentially corporate responsibility), the multifarious nature of harm to the environment will not preclude findings against specific States of violating human rights for failing to carry out their obligations, even if the State is relatively small and has little overall impact on the environmental threat in question. Second, in relation to the status of complainants, the test is more stringent for individual humans than for associations. Groups interested in protecting and preserving the space environment should pay due heed to this jurisprudential development if they want to lay the platform for potential future claims of human rights violations due to spoliation of the outer space environment.
In terms of implementing accountability for human rights, violations of these rights in outer space would typically occur outside of a State’s territorial jurisdiction.206 In this respect, courts, including the International Court of Justice, have confirmed that human rights have an extraterritorial
However, at the conceptual level, harm to the space environment is not as directly linked to human beings as terrestrial environmental harm is.214 This
Applying this to the outer space environment, it must be noted that different forms of harm to the space environment affect human rights in different ways. Space debris, which risks cutting off human access to space, has a clear and demonstrable link to human suffering as set out above. Where State agents taken actions within their jurisdiction, including in a flagged space shuttle, which result in space debris, or otherwise maneuver a space object to as to directly cause debris that could undermine human rights, they will potentially have violated human rights obligations. For other forms of space pollution – such as the introduction of radio waves into outer space – a case-by-case assessment will be required to determine if there is a sufficient link between the environmental harm and human rights deprivation, but the jurisdictional assessment would remain the same as for debris.
When it comes to space active nsas, such as corporations, the question of applying human rights obligations arises both in relation to States and to the corporations themselves. Corporations can impact on human rights through their activities in space, as ‘corporations are usually part of complex supply chains through which, not unlike other business enterprises, they might contribute or be linked to human rights, labour rights and environmental impacts.’217 For State-focused obligations, a corporation may be considered to
Nonetheless, the recognition of the human right to a clean, healthy and sustainable environment marks a significant step towards the broader recognition of a prohibition on serious environmental pollution, which can be extended to the outer space environment in line with several principles of international space law discussed above, most notably the prohibition on causing harmful contamination under Article ix of the Outer Space Treaty. Because space pollution threatens humankind’s very access to space and because of the potential importance of space for human survival in the long-term, it could arguably constitute a significant incursion on the human right to a clean, healthy and sustainable environment.222
2 Conclusion regarding a Prohibition of Space Pollution
As a result of these countervailing strands of interpretive factors, eminent experts have widely divergent views regarding the prohibition of space pollution. Some, such as Professor Hobe, contend that causing space debris is not a violation of international law, at least during normal operations.223 Others, such as Professor Stubbe, argue that causing space debris is definitively prohibited224 on the basis of Article ix of the Outer Space Treaty.225 For present
In addition, several established principles of international environmental law, imported into space law by virtue of Article iii of the Outer Space Treaty could theoretically per se be violated by space pollution. Nonetheless, this application of terrestrially-conceived notions to the extra-terrestrial domain is novel and untested. Whereas it is clear that international environmental law principles can assist the interpretation of the provisions of the Outer Space Treaty, it is more contestable whether those principles can be directly read into this leading convention. Several authors warn that the application of principles of international law by means of Article iii of the Outer Space Treaty cannot be automatic, but must rather be a result of a considerate deliberation whether such application is appropriate and reasonable, and to what extent.227 In this regard, questions arise, for example, whether the no-harm (and also the preventive) principle can be applied to harmful effects emitted from a space object to outer space in general or whether those effects need to specifically
In sum, the robust basis for a prohibition of space pollution under international law is discernible and provides an important foundational platform for the remaining examination of nsa accountability for space pollution. Moreover, given the trend towards regulating anthropocentric harm to the natural environment, and the tendency for definitions of the environment to extend to outer space, the basis for the prohibition of space pollution will most likely grow increasingly robust in the coming years.
Most of the cases are related to torts and contracts, very few cases relate to the environment. See, e.g., Rick Adams, ‘The New York Times Co. v. National Aeronautics and Space Administration’ (available at
See Viikari (2008), p. 6.
Clapham identifies national courts (civil and criminal liability) and the International Criminal Court (individual criminal liability) for nsa liability and relevant international human rights treaty monitoring bodies and courts for State liability (accountability for treaty violations), see Clapham (2006), p. 32.
See, e.g. Fogo, pp. 182–190.
Stubbe (2018), p. 3. See also Viikari (2008), p. 31.
Contrast Hobe (2019), pp. 88–90 with Stubbe (2018), p. 163.
See Chapter 1 (definition of ‘space pollution’). See further, Stubbe (2018).
Yun Zhao, ‘Space Commercialization and the Development of Space Law’ (2018) Oxford Research Encyclopedia of Planetary Science, p. 1.
Viikari (2008), p. 58.
The Outer Space Treaty has 114 State Parties at the time of writing, including all space-faring States (see UN Doc. a/ac.105/c.2/2024/crp.3; unoosa, Status of International Agreements relating to Activities in Outer Space, unoosa (available at:
Isabella Diederiks-Verschoor, ‘Environmental Protection in Outer Space’ (1987) 30 German Yearbook of International Law 144, cited in Zhao (2018), p. 10.
On the evolving interpretation of provisions of international law, see icj, Award in the Arbitration regarding the Iron Rhine (‘Ijzeren Rijn’) Railway (Belgium v. Netherlands) icj Reports 2005, para. 80 (in addition to conceptual or generic terms, ‘new technological developments’ are subject to ‘an evolutive interpretation, which would ensure an application of the treaty that would be effective in terms of its object and purpose’). See also icj, In the Case concerning the Gabčikovo-Nagymaros Project (Hungary v. Slovakia) icj Reports 1997, para. 112 (“By inserting these evolving provisions in the Treaty, the parties recognized the potential necessity to adapt the Project. Consequently, the Treaty is not static, and is open to adapt to emerging norms of international law. By means of Articles 15 and 19, new environmental norms can be incorporated in the Joint Contractual Plan.”).
See Report of the Scientific and Technical Subcommittee on its 42nd session 2005, para. 97 (containing the proposal made in the deliberations of the uncopuos that ‘in order for States to continue having unrestricted access to outer space, all spacefaring nations should be implementing space debris mitigation measures as expeditiously as possible’); Viikari (2008), p. 59.
Viikari (2008), p. 59 (‘Limitations on conducting space activities in environmental terms in particular are dealt with more directly in Article ix, which is the basic provision for all environmental protection of outer space.’).
Paul G. Dembling and Daniel M. Arons, ‘The Evolution of the Outer Space Treaty’, Journal of Air Law and Commerce 33 (1967), p. 440.
Emphasis added.
Larsen (2018), p. 482.
Stubbe (2018), p. 163 (referring to ‘the central question [of] whether space debris pollution of outer space can be characterized as a harmful contamination.’); Hobe (2019), p. 88; Howard A. Baker, ‘Protection of the Outer Space Environment: History and Analysis of Article ix of the Outer Space Treaty’ (1987) 12 Annals of Air and Space Law, p. 158; Viikari (2008), p. 50; Stephen Gorove, ‘Pollution and Outer Space: A Legal Analysis and Appraisal’ (1972) 5 nyu Journal of International Law and Politics, pp. 55–56.
Gordon Chung, ‘The Emergence of Environmental Protection Clauses in Outer Space Treaty: A Lesson from the Rio Principles’ (2018) in Annette Froehlich (ed.), A Fresh View on the Outer Space Treaty (Springer, 2018), pp. 3–5. See also Zwart et. al., pp. 301–302 (‘concerns of harmful contamination that were raised during the drafting process [of the Outer Space Treaty] were largely theoretical. States persistently chose not to engage with the question of what contamination would be considered harmful’).
William R. Kramer, ‘In dreams begin responsibilities – environmental impact assessment and outer space development’ (2017) 19 Environmental Practice, p. 132.
Howard A. Baker, Space Debris: Legal and Policy Implications (Nijhoff, 1989) pp. 3–9.
Baker (1987), pp. 163, 166, 167.
Marchisio (2009), pp. 169–183.
Marchisio (2014), pp. 172–173.
See Hobe, ‘Handbook’ (2019), pp. 729–730; Giulia Pavesi, ‘Legal Consequences of Environmental Pollution in Outer Space’ (2018) in Froehlich (2018), pp. 21–22.
Baker (1987), pp. 163, 166, 167; Larsen (2018), p. 484 (Article i of the Outer Space Treaty, which provides that outer space is the province of all mankind where free utilization without discrimination of any kind must be guaranteed and therefore indicates that ‘continued deposits of space debris that may preclude access to outer space would be contrary to [its terms]’).
See Cirkovic (2022), p. 1080.
Marietta Benkö, Kai-Uwe Schrogl, Denise Digrell, Esther Jolley, Space Law: Current Problems and Perspectives for Future Regulation (Eleven International Publishing, 2005), p. 226; Philip De Mann, Ward Munters, ‘Reciprocal Limits to the Freedom to Use Outer Space by All States: Common but Differentiated Responsibilities?’ (2018) 43 Air and Space Law, p. 1; Timiebi Aganaba-Jeanty, ‘Space Sustainability and the Freedom of Outer Space’ (2018) 14 Astropolitics: The International Journal of Space Politics and Policy, p. 5.
See, e.g. Stubbe (2018), p. 163; Layachi (2020); Annette Froehlich and Vincent Seffinga, National Space Legislation (Springer, 2018), p. 90; Ram S. Jakhu, Joseph N. Pelton, Global Space Governance: An International Study (Springer, 2017), p. 436; George T. Hacket, Space Debris and the Corpus Iuris Spatialis (Gif-sur-Yvette: Editions Frontières, 1994), p. 115; Anja Nakarada Peculjic, Matteo Tugnoli, Promoting Productive Cooperation Between Lawyers and Engineers (igi Global 2019), p. 188. By contrast, see Joanne Wheeler, ‘Space Debris: Legal Framework, Issues Arising and New iso Guidelines in 2010/2011’ (2013) Yearbook on Space Policy 2010/2011; Peter Hulsroj, Spyros Pagkratis, Blandina Baranes (eds.), The Forward Look (Springer), p. 256; Fawaz Haroun, Shalom Ajibade, Philip Oladimeji, and John Kennedy Igbozurike, ‘Toward the Sustainability of Outer Space: Addressing the Issue of Space Debris’ (2021) 9 New Space 1, p. 69. See also Chapter 5 containing national legislation supporting this interpretation, e.g. Austria, Outer Space Act, para. 4(1)(4) and (5) – authorization procedures require operators to ensure precautions for the avoidance of harmful contamination of outer space by space debris (summarized in Martha Mejia-Kaiser, The Geostationary Ring: Practice and Law (Martinus Nijhoff Publishers, 2020), p. 217).
Viviana Iavicoli, ‘The legal regime of outer space in light of the Law of the Sea’ (2015) in Salvatore Aricò (ed.) Ocean Sustainability in the 21st Century (Cambridge University Press, 2015), p. 258; Viikari (2008), p. 50; Zwart et. al (2021), p. 277.
Radi (2023), pp. 6–7.
See Stubbe (2018), p. 154.
Vienna Convention on the Law of Treaties, 23 May 1969, 1155 unts 331 (entered into force on 27 January 1980).
Stubbe (2018), pp. 154–155.
Radi (2023), p. 7.
Viikari (2008), pp. 59–60.
Hobe (2019); Shaw (2008); von der Dunk (2015a), pp. 55–60. See also, Chapter 2, Section 1.2 below.
Viikari (2008), p. 59 (‘preservation of the space environment can be regarded as a basic condition for guaranteeing equal opportunities in exploration and use by all countries.’).
In other words, should debris rise to the level where it is obstructing free access, exploration and use of outer space it could be considered as violating not only the freedoms from Article i of the Outer Space Treaty, but also the prohibition on national appropriation from Article ii of the Outer Space Treaty. For example, due to Article viii of the Outer Space Treaty granting States that nationally register launched objects, jurisdiction over these and any personnel thereof and as furthermore this jurisdiction does not depend on functionality of an object (See Chapter 3, Section 1 below) an abandoned registered object could not lawfully be removed without the respective State´s consent. If the State would be unwilling to grant consent or remove the object itself, this would mean that the object was permanently possessing a part of outer space (such as for example surface area of celestial bodies or an orbital position) thus resulting in de-facto appropriation of outer space, see Sancin, Grünfeld, Ramuš Cvetkovič (2021), pp. 22–25.
Article 3.1.
Viikari (2008), p. 62.
Viikari (2008), p. 63.
Antonella Bini, ‘The Moon Agreement: Its effectiveness in the 21st century’ (2008) 14 European Space Policy Institute Perspectives 14, pp. 1–7. See also von der Dunk (2015a), pp. 99–100, where the author assessed that the provisions of the Moon Agreement in this particular context are not particularly controversial.
Viikari (2008), p. 69.
This also raises the question of whether objects that are not ‘launched’ from Earth but are created in space are covered by the Liability Convention, which primarily places liability on the ‘launching State’; see Ziemblicki and Oralova, pp. 2–3.
For more see P.J. Blount, ‘Renovating Space: The Future of International Space Law’ (2011) 40(1) Denver Journal of International Law and Policy.
See Compendium on Space Debris Mitigation Standards Adopted by States and International Organizations, 8 April 2021.
European Space Agency Director General’s Office (2014), Space Debris Mitigation Policy for Agency Projects, esa/admin/ipol(2014).
See International Organization for Standardization (iso) issuance iso 24113:2023 ‘Space systems – Space debris mitigation requirements’. See also Compendium (2021).
However, sdmg explicitly address States, urging them to formulate national mechanisms to control nsas (space activity operators), see Committee on the Peaceful Uses of Outer Space, Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space, UN Doc. st/space/49 (2010), Point 3, p. 2, declares: ‘Member States and international organizations should voluntarily take measures, through national mechanisms or through their own applicable mechanisms, to ensure that these guidelines are implemented, to the greatest extent feasible, through space debris mitigation practices and procedures’. However, the content and rationale of the sdmg is the minimization and mitigation of space debris emission during normal space operations and therefore seem to be addressed to the space activity operator, often a private actor, see sdmg, Point 4, p. 2: ‘The following guidelines should be considered for the mission planning, design, manufacture and operational (launch, mission and disposal) phases of spacecraft and launch vehicle orbital stages’. This is supported by national legislation incorporating sdmg. On this basis, the sdmg in part address space activity operators, whether States or nsas, and Point 3 of the sdmg simply obliges States and international organizations to ensure sdmg application. Up to date, several States have incorporated sdmg into national legislation, See, e.g., Finland Space Act; Austrian Space Act; French Space Act (all detailed in Chapter 5).
See iadc (2007). However, experts warn that even with full observance of sdmg, mitigation efforts will not be sufficient to resolve the issue if we keep to the status quo (see European Space Agency, Space debris mitigation: the case for a code of conduct (available at
See Compendium (2021).
See Compendium (2021). See also Zhao (2018), p. 4. However, not all of the space faring States require private entities conducting space exploration from their territories to take on environmental protection obligations in order to be licensed; Marboe and Hafner in von der Dunk (1992), p. 63 (Table 1).
icj, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion of 8 July 1996 (i.c.j Reports 1996, p. 226), paras. 68–70.
icj, Nicaragua, paras. 188, 191.
Hilary Charlesworth, ‘Customary International Law and the Nicaragua Case’, (1984–87) 11 Australian Year Book of International Law, p. 24. But see Öberg (2005), pp. 899–900.
See: UN General Assembly Resolution a/res/68/74, adopted on 11 December 2013 (available at
UN General Assembly Resolution a/res/73/91, adopted on 18 December 2018; Cirkovic (2022), p. 6.
uncopuos, Guidelines for the Long-term Sustainability of Outer Space Activities, UN Doc. a/ac.105/2018/crp.20 (28th June 2018), para.15.
For example, the prohibition of genocide is emphatic and detailed. See Genocide Convention, Article 1.
Experts, however, diverge on the question whether Article iii imports all relevant provisions and principles of international law and generally divide into two potential interpretations. A natural reading is that Outer Space Treaty Article iii neither expands nor restricts existing international law, but simply holds that States must carry out activities under Outer Space Treaty without violating international law. That means that, for example, if an existing international obligation is limited to Earth, or a specific area thereof, then that obligation is not transposed to outer space by the Outer Space Treaty. An alternative reading is that Article iii of the Outer Space Treaty automatically transposes obligations under international law to the outer space environment. Thus, the Basel Convention on movement of toxic goods would automatically apply to activities in space, irrespective of definitions in the Basel Convention as to its ambit of application. Dennerley (2018) writes in favour of this alternative reading: ‘Article iii provides for the inclusion of customary rules of international law relating to state liability and state responsibility as elements of the regime of space law.’ Several other authors support such a view; Sergio Marchisio, ‘The itu Regulatory System: a Self-Contained Regime or a Part of International Law?’ (2014) in Guilhem Penent (ed.) Governing the Geostationary Orbit Orbital Slots and Spectrum Use in an Era of Interference (Space Policy Programme, 2014), pp. 75, 78; Stephan Hobe and Erik Pellander, ‘Space Law: A ‘Self-Contained Regime?’ (2012) in Stephan Hobe, Steven Freeland (eds.) In Heaven as on Earth? The Interaction of Public International Law on the Legal Regulation of Outer Space (Bonn: Institute of Air and Space Law of the University of Cologne, 2012), p. 7.
Olivier Ribbelink, ‘Article iii’ (2009) in Stephan Hobe, Bernhard Schmidt-Tedd, Kai-Uwe Schrogl, Gérardine Meishan Goh (eds.) The Cologne Commentary on Space Law: Vol. i (Carl Heymanns, 2009), pp. 64–70.
Marchisio (2014), pp. 75, 78; Hobe, Pellander (2012), p. 7; Hobe (2019), pp. 53–55.
See Fawaz Haroun, Shalom Ajibade, Philip Oladimeji, John Kennedy Igbozurike, ‘Toward the Sustainability of Outer Space: Addressing the Issue of Space Debris’, (2012) 9:1 New Space, 63–71 (‘In recognition of the importance of space being a common heritage of mankind, a proper legal regime should extend the environmental law principles applicable on Earth to space. This should include the precautionary principle, the polluter-pays principle, the transboundary harm principle, environmental impact assessment, among others.’); Brunner and Soucek, Outer Space in Society (2011), p. 382; Viikari (2008), pp. 119–206.
Ribbelink (2009), pp. 64–65; Hobe (2019), pp. 53–56; Lachs (2010), pp. 11–17; Fogo (2017), p. 197; Lyall and Larsen, pp. 39–43.
Pierfrancesco Breccia, ‘Article iii of the Outer Space Treaty and Its Relevance in the International Space Legal Framework’ (2016) in 67th International Astronautical Congress (iac), pp. 1, 3.
For a discussion of systemic integration, whereby treaty provisions are interpreted consistently with the broader framework of international law; see Campbell McLachlan KC, The Principle of Systemic Integration in International Law (2024; online edn, Oxford Academic); Campbell McLachlan, ‘The Principle of Systemic Integration and Article 31(3)(C) of the Vienna Convention’, International and Comparative Law Quarterly, 54 (2005), p. 318.
Note that there is a difference between the phrase ‘in accordance with’ in Article iii of the Outer Space Treaty and ‘apply’ in Article 21 of the Rome Statute of the icc. Whereas the latter explicitly empowers the icc to rely on external legal sources beyond the Rome Statute (and Elements of Crimes and Rules of Procedure), the former is more ambiguous and is arguably oriented towards interpreting in light of international law rather than importing external legal sources to substantively rely on per se.
Concerning systemic integration, see McLachlan (2024); Lauren Nishimura, Adaptation and Anticipatory Action: Integrating Human Rights Duties into the Climate Change Regime (Brill, 2022) (which seeks to systemically integrate ihrl obligations into a key area of iel); Karen Hulme, ‘Using International Environmental Law to Enhance Biodiversity and Nature Conservation During Armed Conflict’, (2022) 20 Journal of International Criminal Justice, pp. 1155–1190 (which conducts a rule-by-rule and treaty-by-treaty assessment of the complementary aspects of these two branches for the protection of the environment during armed conflict).
This contrasts with Article 21 of the Rome Statute of the International Criminal Court, for example, which explicitly allows the Court to apply exogenous facets of international law, such as customary and conventional international humanitarian law.
International Law Commission (2006), Report of the ilc to the fifty-eight session of the General Assembly, a/61/10 [Fragmentation Report], paras. 36, 488; Anne Peters, ‘The refinement of international law: From fragmentation to regime interaction and politicization’ (2017) 15(3) International Journal of Constitutional Law, pp. 690, 692, 702. For more on the role of lex specialis in combating fragmentation of international law regarding the regulation of space activities see Iva Ramuš Cvetkovič, Space law as lex specialis to international law (Master Thesis) (2021) (University of Ljubljana, Faculty of Law) (available at
Breccia (2016), p. 8.
Breccia, (2016) ‘Article iii of the Outer Space Treaty and Its Relevance in the International Space Legal Framework’, 67th International Astronautical Congress (iac), 2016, p. 3 (‘In this sense, although every field of international relations would be regulated most directly by its lex specialis, it does not mean that a significant part of international law, such as rules of customary international law and general principles of international law, are not applicable generally.’). See also Lachs (2010), p. 11–17.
Breccia (2016), p. 8. See also Viikari (2008), pp. 22–23.
Breccia (2016), p. 8. An example of a principle potentially requiring adaptation is that of common-but-differentiated responsibilities, given that some States have simply no space program whatsoever; see below Chapter 5.
Draft Code of Crimes Against the Peace and Security of Mankind, Yearbook of the International Law Commission (1991), p. 107, para. 4 reads ‘the words ‘natural environment’ should be taken broadly to cover the environment of the human race and where the human race develops, as well as areas the preservation of which is of fundamental importance in protecting the environment. These words therefore cover the seas, the atmosphere, climate, forests, and other plant cover, fauna, flora and other biological elements.’.
Treaty Banning Nuclear Weapon Tests in the Atmosphere, 5 August 1963, 480 unts 43 (entered into force on 10 October 1963), see Article i: ‘in Outer Space and Under Water’.
See, e.g., United Nations General Assembly (2006), Report of the Committee on the Peaceful Uses of Outer Space, a/61/20, p. 19, where it is stated that ‘Efforts should continue to be made to devise the technical ability to begin removing existing space debris from their orbits in order to halt the decline in the space environment.’; Guidelines for the Long-term Sustainability of Outer Space Activities, UN copuos, UN Doc. a/ac.105/2018/crp.20 (27th June 2018); unga Resolution, UN Doc. a/res/77/120 (15th December 2022); unga Resolution, UN Doc. a/res/77/121 (15th December 2022); unga Resolution, UN Doc. a/res/73/6 (31st October 2018); uncopuos Report, UN Doc. a/77/20 (30th June 2022).
For example, the European Space Policy Institute, see Space Environment Capacity, espi Report 82 (April 2022); European Space Agency, see esa’s Annual Space Environment Report, esa Space Debris Office Report (22nd April 2022); Thomas Colvin, John Karcz, and Grace Wusk, ‘Cost and Benefit Analysis of Orbital Debris Remediation’ nasa Office of Technology, Policy, and Strategy Report (10 March 2023) (available at
See Council of Europe, Model Act on the Protection of the Environment 1994, Dela/Model Act (94)1, Article 1(b)(i).
Independent Expert Panel, Definition of Ecocide, June 2021 (
See, e.g., Hobe (2019); Stubbe (2018); Viikari (2008); Dennerley (2018); Tateo Goka, ‘The Space Environment: Natural and Induced’ (2009) in Gary Eugene Musgrave, Axel (Skip) M. Larsen, Tommaso Sgobba (Eds.) Safety Design for Space System (Butterworth-Heinemann, 2009); Annette Froehlich (ed.), Space Resource Utilization A View from an Emerging Space Faring Nation, (espi/Springer, 2018); Isabella Diederiks-Verschoor and Vladimir Kopal, An Introduction to Space Law (3rd Revised Version) (Wolters Kluwer International, 2008); Philip De Man, The Commercial Exploitation of Outer Space and Celestial Bodies – A Functional Solution to the Natural Resource Challenge, in Mark J Sundahl and V Gopalakrishnan (eds) New Perspectives on Space Law (International Institute of Space Law, 2011).
Marie-Louise Larsson, ‘Legal Definitions of the Environment and of Environmental Damage’ (1999) Scandinavian Studies in Law (available at
Stubbe (2018), p. 168.
Trail Smelter Arbitration (USA v. Canada), Decision of 16 April 1938, published in: 33 American Journal of International Law 1, 1938 (‘Trail Smelter Arbitration’), p. 182; and Trail Smelter Arbitration (USA v. Canada), Decision of 11 March 1941 (‘Trail Smelter Arbitration2’), Published in 35 American Journal of International Law 4, 1941, p. 716.
See icj, Corfu Channel Case (U.K. v. Albania), Judgment of 15 December 1948 (icj Reports 1948, p. 15).
See icj, Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment of 20 April 2010 (icj Reports 2010, p. 14), para. 101 (‘The Court points out that the principle of prevention, as a customary rule, has its origins in the due diligence that is required of a State in its territory. It is “every State’s obligation not to allow knowingly its territory to be used for acts contrary to the rights of other States” (Corfu. Channel (United Kingdom v. Albania), Merits, Judgment, i.c.j. Reports 1949, p. 22). A State is thus obliged to use all the means at its disposal in order to avoid activities which take place in its territory, or in any area under its jurisdiction, causing significant damage to the environment of another State. This Court has established that this obligation “is now part of the corpus of international law relating to the environment” (Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, i.c.j. Reports 1996 (i), p. 242, para. 29).’).
Radi (2023), p. 7.
Trail Smelter Arbitration 2.
icj, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion of 8 July 1996 (icj Reports 1996), para. 29; icj, Case Concerning the Gabčikovo-Nagymaros Project (Hungary v. Slovakia), Judgment of 25 September 1997 (icj Reports 1997, p. 7), para. 53.
Draft articles on Prevention of Transboundary Harm from Hazardous Activities with Commentaries (dapthaa), Yearbook of the International Law Commission, Volume ii, Part ii (2001), Article 2(b).
dapthaa, Article 2(b).
In the Trail Smelter case, the term ‘serious consequence’ is used. The term ‘seriously’ is further highlighted in the Lake Lanoux Arbitration (France v. Spain), Decision of 16 November 1957, 12 r.i.a.a. 281, 24 i.l.r. 101.
dapthaa, p. 152, para. 4.
Jasper Schellenkens, The Legality of Anti-satellite Weapons (University of Malta Thesis, 2008). p. 32 (‘any activity that causes damage to the environment in space can be considered a violation of Principle 2 of the Rio Declaration’).
Dennerley (2018), p. 296.
Stubbe (2018), pp. 187, 197–198 citing inter alia Andrea Bianchi, ‘Environmental Harm Resulting from the Use of Nuclear Power Sources in Outer Space: Some Remarks on State Responsibility and Liability’ (1991) in Francesco Francioni (ed.) International Responsibility for Environmental Harm, (Graham and Trotman, 1991), p. 237; Nicolas Matte, ‘Environmental Implications and Responsibilities in the Use of Outer Space’ (1989) 14 Annals of Air and Space Law, pp. 419–421;Wolfgang Graf Vitzthum, Volkerrecht, 5th edition (De Gruyter Recht, 2010), p. 451; Lyall and Larsen (2009), p. 303. See also Breccia (2016), p. 8.
See icj, Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment, para. 101.
Mara Tignino, Christian Bréthaut, ‘The role of international case law in implementing the obligation not to cause significant harm’ (2020) 20 International Environmental Agreements: Politics, Law, and Economics, pp. 639, 640; Adrian Di Giovanni, ‘A Pebble in the Shoe: Assessing the Uses of Do No Harm in International Assistance’ (2014) 47(2) Law and Politics in Africa, Asia and Latin America, p. 218.
icj, Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment, para. 101.
See Chapter 5. See also Hobe (2019); Viikari (2008), pp. 104–111.
See Meinhard Schröder, ‘Precautionary Approach/Principle’ (2014) in Rüdiger Wolfrum (ed) Max Planck Encyclopedia of Public International Law (online edition), paras. 16–21 (disputing that the precautionary principle is customary international law). But see Michael Bothe, ‘Protection of the Environment in Relation to Armed Conflicts’ (2021) in Dieter Fleck (ed.) The Handbook of International Humanitarian Law, 4th ed. (Oxford University Press, 2021), p. 343 (arguing that the principle of precaution is a ‘fundamental rule of modern customary environmental law’); Haroun et al. (2021), 67 (arguing that the precautionary principle is established in customary international law and citing the ‘mox Plant Case, Ireland v United Kingdom, Order, Request for Provisional Measures, itlos Case No 10, icgj 343 (itlos 2001), 3rd December 2001, International Tribunal for the Law of the Sea [itlos]). See generally Matthew Gillett, Prosecuting Environmental Harm before the International Criminal Court (Cambridge University Press, 2022), pp. 170–173.
Jose Felix Pinto-Bazurco, ‘Deep Dive: The Precautionary Principle’ International Institute for Sustainable Development (23 October 2020) (available at
Viikari (2008), p. 134.
Larsen (2018), p. 491. See also Freeland and Ireland-Piper (2022), p. 21 (‘The precautionary principle might possibly be relevant, although not necessarily directly applicable, to both human rights and human activities in outer space, particular given that so much is unknown about the environmental consequences for Earth of destabilizing the Moon through mining activities.’).
Viikari (2008), p. 157.
For example the responsibility and liability regimes included in the space treaties exemplify elements of precautionary approach, for a more in depth analysis see: Claudia Cinelli and Katarzyna Pogorzelska, ‘The Current International Legal Setting for the Protection of the Outer Space Environment: The Precautionary Principle Avant La Lettre’ (2013), 22 reciel 2, pp. 186–201; Paul B. Larsen, ‘Application of the Precautionary Principle to the Moon’ (2006), 71(2) Journal of Air Law and Commerce, pp. 295–306.
See Cinelli and Pogorzelska (2013), p. 191. See further Larsen (2006), pp. 295–306; Olavo Bittencourt Neto, ‘Preserving the outer space environment: The ‘precautionary principle’ approach to space debris’ (2013) International Institute of Space Law, p. 341.
1972 Stockholm Declaration, Principles 2, 3, 4, 7 and Preamble.
1992 Rio Declaration, Principles 1, 4, 5, 7, 8, 9, 12, 20, 21, 22, 24, 27; Virginie Barral, ‘Sustainable Development in International Law: Nature and Operation of an Evolutive Legal Norm’ (2012) 23(2) European Journal of International Law, pp. 377, 379.
This principle has also been incorporated into numerous and various international and national instruments such as the 2002 World Summit on Sustainable Development; the 1991 Protocol on Environmental Protection to the Antarctic Treaty; the 1992 Convention on Biological Diversity; the 1992 UN Framework Convention on Climate Change (Article 3.4); the 1992 Convention on Biological Diversity (Article 6(b)).
United Nations Agenda 21 (unced Report, a/conf.151/26/Rev.1 (vol. i)) (1993).
See Patricia Birnie and Alan Boyle, International Law and the Environment (2nd ed. Oxford University Press, 2002), p. 87 (referring to numerous national acts of developed countries); Viikari (2008), p. 134.
Report of the World Commission on Environment and Development: ‘Our Common Future’, UN Doc. a/42/427, Annex i, 4 August 1987, 54.
icj, Case Concerning the Gabčikovo-Nagymaros Project (Hungary v. Slovakia), Judgment, para. 140.
Viikari (2008), p. 129 and Ferreira-Snyman (2023), p. 3.
See Birnie-Boyle (2002), p. 4; Viikari 2008, p. 130.
Viikari 2008 p. 130; see also Birnie-Boyle (2002), p. 84.
See also Principle 12 of the Rio Declaration, which declares that the sovereign right of states ‘to exploit their own resources pursuant to their own environmental and developmental policies’, tempered by the responsibility for transboundary environmental protection.
Viikari (2008), pp. 131–132.
See also Verschuuren (2003), pp. 46–49, 144; Viikari (2008), pp. 133–134.
See also Larsen (2018), p. 481.
See Vladimir Atanasov and Gianluigi Baldesi, ‘An Analysis of Two Space Business Opportunities’ in Stella Tkatchova, Space-Based Technologies and Commercialized Development: Economic Implications and Benefits (igi Global, 2011), p. 210.
Declaration of the United Nations Conference on the Human Environment (Stockholm Declaration), 15 December 1972. Stockholm Principle 21 points to international acceptance of the proposition that states are also required to protect global common areas, including Antarctica and those areas beyond the limits of national jurisdiction, such as the high seas, deep sea-bed, and outer space. Principle 21 (which was reproduced in Principle 2 of the Rio Declaration) provides that ‘States have, in accordance with the Charter of the United Nations and the principle of international law, the sovereign right to exploit their own resources pursuant to their own environmental policies, and the responsibility that activities within their jurisdiction or control do not cause damage to the environment of other states or of areas beyond the limits of national jurisdiction.’
uncopuos, UN Doc. a/ac.105/2018/crp.20 (28 June 2018).
It is disputed whether the principle of sustainable development constitutes a principle or rather a goal with broad buy-in. Given the lack of consensus on its specific content, there is considerable divergence in its interpretation and application; see Birnie-Boyle (2002), p. 45; Viikari (2008), p. 134. Moreover, the anthropocentrism and utilitarianism at the core of this formulation limits its eco-centric value (the Rio Declaration states that ‘human beings are at the centre of concerns for sustainable development’, and the Stockholm Declaration preamble states that ‘of all things in the world, people are the most precious’ – but does mention in Principle 4 humankind’s special responsibility to wildlife and its habitat), See, e.g., Verschuuren (2003), pp. 20–25; Viikari (2008), pp. 129, 131.
However, the Independent Expert Panel which has proposed a definition of ecocide has placed an analogous concept to the idea of sustainable development (namely balancing environmental harm against social and economic benefits) at the heart of its definition of Ecocide. For a critique, see Matthew Gillett, ‘A Tale of Two Definitions: Fortifying Four Key Elements of the Proposed Crime of Ecocide’, Opinio Juris, 20 June 2023 (
Integrating environmental considerations in developmental considerations is more likely to guarantee environmental values are taken into account in decision-making processes than separating the two. This has been demonstrated by Principle 4 of the Rio Declaration, which highlights the fundamental role of sustainable development principle in environmental management and protection, which ‘cannot be considered in isolation from it.’ Therefore, the principle of sustainable development is nonetheless relevant and valuable to space activities, in particular during the planning and design phases. For more see Viikari (2008), p. 134.
Edith Brown Weiss, ‘Climate Change, Intergenerational Equity, and International Law’ (2008) Vermont Journal of Environmental Law, pp. 622–623.
Freeland and Ireland-Piper (2022), pp. 21–22.
As of January 2024, the number will stand at 17, following Saudi Arabia´s withdrawal in January of 2023.
Report of United Nations sixty-second session of the Committee on the Peaceful Uses of Outer Space, a/62/20, Annex, p. 47.
uncopuos Guidelines for the Long-term Sustainability of Outer Space Activities, para. 4.
Viikari (2008), p. 65 (‘[o]uter space is an environment that in principle is shared by all states, populations and generations, and its contamination could jeopardize their rights of exploration and use.’).
Radi (2023), p. 2 (referring for support for the principle to Article i of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (adopted 27 January 1967, entered into force 10 October 1967) 610 unts 205).
Breccia (2016), p. 8.
See also Stephen Gorove, ‘The Concept of “Common Heritage of Mankind”: A Political, Moral or Legal Innovation?’ (1972) 9 San Diego Law Review, p. 394.
uncopuos Report (2007), para. 44.
Viikari (2008), pp. 138, 178–179.
See, for example, United Nations Framework Convention on Climate Change, 9 May 1992, 1771 unts 107 (entered into force on 21 March 1994); Vienna Convention for the Protection of the Ozone Layer, 22 March 1985, 1513 unts 323 (entered into force on 22 September 1988); Convention on Biological Diversity, 22 May 1992, 1760 unts 79, (entered into force on 29 December 1993).
Viikari (2008), pp. 289–290.
Viikari (2008), p. 181.
Emphasis added.
unga Resolution 41/65.
Hobe (2010), p. 876. See Chapter 1.
See, e.g. United Nations Framework Convention on Climate Change, 9 May 1992, 1771 unts 107 (entered into force on 21 March 1994).
Viikari (2008), p. 182.
Viikari (2008), p. 182.
See Svitlana Kravchenko, Tareq M.R. Chowdhury, Jahid Hossain Bhuiyan, ‘Principles of International Environmental Law’ (2013) in Shawkat Alam, Jahid Hossain Bhuiyan, Tareq M.R. Chowdhury and Erika J. Techera (eds.) Routledge Handbook of International Environmental Law (Routledge, 2013), p. 54.
See generally Birnie–Boyle (2002), pp. 568–588. See also Peter Stubbe, ‘Common but Differentiated Responsibilities for Space Debris – New Impetus for a Legal Appraisal of Outer Space Pollution’ (2010), European Space Policy Institute Perspectives, p. 11 (‘the principle must not be construed in a way that tempts states to refrain from mitigation measures. … Only collective action can reverse the trend of ongoing degradation of the outer space environment which is in the interest of all states – be it developing or developed’).
Viikari (2008), p. 183.
Ferreira-Snyman (2013), pp. 35–36; Philip De Man, Ward Munters, ‘Reciprocal Limits to the Freedom to Use Outer Space by All States: Common but Differentiated Responsibilities?’ (2018) 41 Air and Space Law, p. 21.
See Viikari (2008), 183, Uchitomi (2000), at 77.
Uchitomi (2000), pp. 77, 80; Viikari (2008), p. 182.
Viikari (2008), 182.
Uchitomi (2000), pp. 77, 80; Viikari (2008), p. 182.
See, e.g., Committee on the Peaceful Uses of Outer Space, Report of the Scientific and Technical Subcommittee on its 42nd session, held in Vienna from 21 February to 4 March 2005, UN Doc. a/ac.105/848 (21 February – 4 March 2005), para. 99.
Viikari (2008), p. 182.
Viikari (2008), p. 184.
oecd, Recommendation of the Council on Guiding Principles concerning International Economic Aspects of Environmental Policies, 2020; Rio Declaration Art. 16.
Haroun et. al. (2021), p. 68.
Viikari (2008), pp. 202, 203.
unga Resolution 1803 (xvii), 14 December 1962, ‘Permanent sovereignty over natural resources’, preamble.
unga Resolution 1803 (xvii), 14 December 1962, ‘Permanent sovereignty over natural resources’.
Convention on Biological Diversity 1992, 1760 unts 30619, Preamble.
Convention concerning the Protection of the World Cultural and Natural Heritage, 23 November 1972 (‘World Heritage Convention’), 1037 unts 151, article 2.
See von der Dunk (2015a), p. 58.
See in Article 11(1). Article 11 goes on to provide that ‘Neither the surface nor the subsurface of the Moon, nor any part thereof or natural resources in place, shall become property of any State, international intergovernmental or non-governmental organization, national organization or non-governmental entity or of any natural person.’
See Vienna Convention on the Law of Treaties 1969, Article 31.
Eliana Cusato, ‘From Ecocide to Voluntary Remediation Projects: Legal Responses to Environmental Warfare in Vietnam and the Spectre of Colonialism’ (2018) 19 Melbourne Journal of International Law (‘Cusato (2018)’), pp. 499–500; Elizabeth Maruma Mrema, Carl Bruch, and Jordan Diamond, Protecting the Environment during Armed Conflict: An Inventory and Analysis of International Law (United Nations Environment Programme, 2009) (unep, 2009), p. 12.
Convention on the Prohibition of Military and Other Hostile Use of Environmental Modification Techniques (enmod), 10 December 1976, 1108 unts 151 (entered into force on 5 October 1978), p. 151, see Article ii.
See Roman Reyhani, Protection of the Environment During Armed Conflict, 14 Missouri Environmental Law and Policy Review 323 (2006); Yoram Dinstein, The Conduct of Hostilities Under the Law of International Armed Conflict 178 (Cambridge University Press, 2004), p. 1801.
Breccia (2016), p. 8.
Breccia (2016), p. 8.
Lyall and Larsen (2009), p. 275.
Viikari (2008), p. 55.
Viikari (2008), p. 54.
See unga Resolution a/res/76/300 The human right to a clean, healthy and sustainable environment, a/res/76/300 (28 July 2022).
unga, hrc, a/hrc/res/48/13 (18 October 2021).
unga Resolution a/res/76/300, paras. 2–3.
IACtHR, Comunidades Indígenas Miembros de la Asociación Lhaka Honhat (Nuestra Tierra) v. Argentina (6 February 2020) (‘Lhaka Honhat’), para. 203.
See above Chapters 1 and 2, Section (2).
EctHR, Giacomelli v. Italy, Judgment of 2 November 2006 (Application no. 59909/00), where the EctHR recognized that the applicant’s right to respect for her home and her private and family life was impaired by the negative environmental impacts of an industrial plant nearby; the currently pending EctHR case Verein KlimaSeniorinnen Schweiz v. Switzerland, application lodged on 26 November 2020 (Application no. 53600/20); and Inter-American Court of Human Rights, Advisory Opinion oc-23/17 from 2018 (referring to the Inter-American cases recognizing an autonomous right to a healthy environment).
Human Rights Council (2012), Report of the Independent Expert on the issue of human rights obligations relating to the enjoyment of a safe, clean, healthy and sustainable environment (Preliminary Report), UN Doc. a/hrc/22/43, para. 10; see also: Inter-American Court of Human Rights, State Obligations in Relation to the Environment in the Context of the Protection and Guarantee of the Rights to Life and to Personal Integrity, Advisory Opinion of 15 November 2017 (oc-23/17), pp. 22–23 (In the Advisory Opinion oc-23/17 from 2018, the Inter-American Court of Human Rights stated that there is an undeniable interrelationship between realization of human rights and the protection of the environment; as the human rights, including the right to a healthy environment, are affected by degradation to the environment, see paras. 47, 48).
See, e.g. Human Rights Committee, Portillo Cáceres et al. v. Paraguay, Communication No. 2751/2016, Views of 25 July 2019, UN Doc. ccpr/c/126/d/2751/2016; EctHR, Öneryıldız v. Turkey, Grand Chamber Judgment of 30 November 2004 (Application no. 48939/99), pp. 6, 59 (disposition); ECtHR, Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, no. 53600/20, judgment (Grand Chamber), 9 April 2024, para. 435. See also Freeland and Ireland-Piper (2022), p. 16.
See Freeland and Ireland-Piper (2022), pp. 16–17.
ECtHR, KlimaSeniorinnen, para. 472.
ECtHR, KlimaSeniorinnen, para. 487, 502. Specifically, it held that, in cases of climate change, for individuals ‘(a) the applicant must be subject to a high intensity of exposure to the adverse effects of climate change, that is, the level and severity of (the risk of) adverse consequences of governmental action or inaction affecting the applicant must be significant; and (b) there must be a pressing need to ensure the applicant’s individual protection, owing to the absence or inadequacy of any reasonable measures to reduce harm’. For associations, it must be shown that they are ‘(a) lawfully established in the jurisdiction concerned or have standing to act there; (b) able to demonstrate that it pursues a dedicated purpose in accordance with its statutory objectives in the defence of the human rights of its members or other affected individuals within the jurisdiction concerned, whether limited to or including collective action for the protection of those rights against the threats arising from climate change; and (c) able to demonstrate that it can be regarded as genuinely qualified and representative to act on behalf of members or other affected individuals within the jurisdiction who are subject to specific threats or adverse effects of climate change on their lives, health or well-being as protected under the Convention.’ Notably, the association does not need to show that the victims it represents would have specifically met the criteria for individuals.
ECtHR, KlimaSeniorinnen, para. 442.
ECtHR, KlimaSeniorinnen, para. 444.
ECtHR, KlimaSeniorinnen, para. 420.
ECtHR, KlimaSeniorinnen, paras. 526 535.
ECtHR, KlimaSeniorinnen, para. 573.
In KlimaSeniorinnen extra-territoriality of effects was raised by the respondent State but dismissed by the Court, as there was sufficient conduct by the State within its territory, and the victims were located within its jurisdiction, which enabled the Court to proceed.
See, e.g. Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, i.c.j. Rep. 136 (July 2004), para. 109. See also Noam Lubell, Extraterritorial Use of Force Against Non-State Actors, (Oxford University Press, 2010) p. 193.
Joseph Sinchak, ‘The Extraterritorial Application of Human Rights Treaties: Al-Skeini et al. v. United Kingdom (2011)’ (2013) 3 Pace International Law Review, pp. 419–425; Samantha Besson, ‘Due Diligence and Extraterritorial Human Rights Obligations – Mind the Gap!’ (2020) 9(1) esil Reflections, p. 3; Theodor Meron, ‘Extraterritoriality of Human Rights Treaties’ (1995) 89(1) American Journal of International Law, pp. 78–80.
Lubell (2010), p. 212.
Macchi (2025), pp. 54, 76 referring to cescr, General comment 24 on State obligations under the International Covenant on Economic, Social and Cultural Rights in the context of business activities (2017) e/c.12/gc/24; Inter-American Court of Human Rights, Advisory Opinion oc-23/17, ‘The environment and human rights’ (2017), paras. 101–103.
See Olivier De Schutter et al., ‘Commentary to the Maastricht principles on extraterritorial obligations of states in the area of economic, social and cultural rights’ (2012) 34(4) Human Rights Quarterly, pp. 5–8.
Freeland and Ireland-Piper (2022), pp. 8–9.
Ribbelink (2009); Hobe (2019); Annette Froehlich and Claudiu Mihai Taiatu, Space in Support of Human Rights (espi/Springer, 2022), pp. 21–29; Macchi (2025), pp. 53–54.
Baker (1987), p. 169 (‘Different characteristics of outer space and terrestrial environments demand different approaches; although the principles may be identical, the details vary considerably.’). See also Lachs (2010), p. 106.
Thirlway (1972), p. 147 (‘The reason why international law is built round States is not because they have selfishly created such a system, or fought off any strivings for equality on the part of other entities: it is because they represent the interests of their human citizens in general terms, in the area where it matters, literally ‘on the ground’’).
Lubell (2010), pp. 230–231.
Macchi (2025), pp. 50–51.
Outer Space Treaty, Article vi. See also Chapter 3, Section 1.
Macchi (2025), pp. 61–62.
However, determining which State is the ‘appropriate State’ can be subject to interpretation, as discussed above.
See Chapter 4, Section 2.4. See also Macchi (2025), p. 70.
Freeland and Ireland-Piper (2022), pp. 17–18.
Hobe (2019), pp. 114–115.
Stubbe (2018), p. 163.
Stubbe (2018), p. 154 (‘article ix sentence 2 of the Outer Space Treaty further obliges states not to contaminate outer space in a harmful manner and to refrain from adversely changing the environment of the Earth.’). Although the second sentence of Article ix reads superficially as though the obligations are limited to when conducting studies and exploration, Stubbe and others have argued that this appears to be poor drafting rather than reflecting any intent to limit the ambit of these responsibilities; Stubbe (2018), p. 154 citing Frantzen, ‘Umweltbelastungen durch Weltraumaktivitaten’ (1991) in Handbuch des Weltraumrechts (Carl Heymanns Verlag, 1991), pp. 611–612; Peter Malanczuk, ‘Review of the Regulatory Regime Governing the Space Environment’ (1996) 45(1) Zeitschrift fur Luft und Weltraumrecht, p. 47.
Ribbelink (2009), pp. 64–69 (noting nonetheless that a considerable portion of conventional and customary international law is applicable to outer space). See also Breccia (2016), p. 8.
Stubbe (2018) considers this not to preclude the application of the ‘no harm’ principle; notwithstanding the wording of the original arbitral decision referring to damage to another State or its nationals or property.