| ag | Advocate General |
| bit | Bilateral Investment Treaty |
| ceta | Comprehensive Economic and Trade Agreement |
| cjeu | Court of Justice of the European Union |
| ct | Constitutional Treaty |
| cta | Common Travel Area |
| dup | Democratic Unionist Party |
| ec | European Community |
| echr | European Convention on Human Rights |
| ECtHR | European Court of Human Rights |
| ecj | European Court of Justice |
| eea | European Economic Area |
| eec | European Economic Community |
| efta | European Free Trade Association |
| ehic | EU health insurance card |
| EU | European Union |
| euwa | European Union (Withdrawal) Act |
| fcc | German Federal Constitutional Court |
| fide | International Federation for European Law |
| gfa | Good Friday Agreement |
| ics | Investment Court System |
| igc | Intergovernmental Conference |
| ima | Independent Monitoring Authority for the Citizens’ Rights Agreements |
| ira | Irish Republican Army |
| pca | Permanent Court of Arbitration |
| pcij | Permanent Court of International Justice |
| pm | Prime Minister |
| tca | Trade and Cooperation Agreement |
| teu | Treaty on European Union |
| tf50 | Task Force on Article 50 |
| UK | United Kingdom |
| ukip | UK Independence Party |
| vclt | Vienna Convention on the Law of Treaties |
| wa | Withdrawal Agreement |