This handbook provides comprehensive and expert analysis of the impact of the Brexit process and the withdrawal of the United Kingdom from the European Union on existing and future EU-UK relations within the context of both EU and international law.

Juan Santos Vara is Professor of Public International Law and European Law, Jean Monnet Chair in EU External Action, and Coordinator of the European Joint Master's in Strategic Border Management (Frontex) at the University of Salamanca, Spain.

Ramses A. Wessel is Professor of European Law at the University of Groningen, the Netherlands. He is also Vice-President of the European Society of International Law (ESIL) and co-founder of the Centre for the Law of EU External Relations (CLEER) in The Hague.

Polly R. Polak is PhD candidate in EU law funded by the Regional Government of Castille and Leon, University of Salamanca, Spain, where she also lectures in EU Law and International Relations and coordinates the Master's degree in EU Studies.

1. The Implications of Brexit for EU and UK External Relations: An Introduction Part I: The Framework for the Future Relationship between the EU and the UK 2. Towards the Formulation of the 'Brussels Criteria': The Values and Principles Underlying EU Withdrawal and Their Application in Future Contexts 3. In the Twilight Zone: The Transition Period in the Withdrawal Agreement 4. Parliamentary Involvement in the Negotiations on the EU-UK Trade Agreement 5. EU Withdrawal Law After Brexit: The Emergence of a Unique Legal Procedure Part II: Brexit and Existing EU International Agreements 6. Managing Brexit: Trade Agreements Binding on the UK Pursuant to its EU Membership 7. Come Fly With Me? Brexit and Air Transport 8. Outside the Opt-out: Legal Consequences of the UK's Withdrawal from the EU for External Action in the AFSJ 9. Copy-Pasting or Negotiating? Post-Brexit Trade Agreements between the UK and Non-EU Countries Part III: International Organizations and EU Diplomacy after Brexit 10 EU-UK Relations at the WTO: Towards Constructive Creative Competition 11. Brexit and its Implications for the EU in the UN Security Council 12. EU Diplomacy after Brexit 13. Brexit and Fisheries: International Law Issues, Participation in RFMOs, Reciprocal Access and the Future Part IV: Common Foreign, Security and Defence Policy after Brexit 14. Post-Brexit Participation of the UK in EU Foreign, Security and Defence Policy 15. UK Sanctions Policy after Brexit: From Dependence to Autonomy? 16. EU Sanctions Policy and the Alignment of Third Countries: Relevant Experiences for the UK? 17. EU Crisis Management Operations and International Responsibility Post-Brexit Part V: Brexit and Specific International Arrangements 18. Brexit and EU Agencies: Opting-in from the Outside? 19. Disentangling the UK from EU Environmental Agreements after Brexit: The Challenges Posed by Mixed Agreements and Soft Law 20. The Future of Judicial Cooperation in Criminal Matters between the EU and the UK Part VI: Contested and External Effects of Brexit 21. The Implications of the Withdrawal Agreement for Gibraltar: Is Spain Taking Back Control? 22. Brexit and International Legal Sovereignty 23. The Cross-Channel Reach of EU Law in the UK Post-Brexit