The European Union plays a significant role in international affairs. International Law and the European Union examines the impact this has had on public international law by integrating perspectives from both EU law and international law. Its analysis focuses on fields of public international law where the EU has had an influence, including customary international law, the law of treaties, international organizations, international dispute settlement, and international responsibility. International Law and the European Union shows how the EU has had a subtle but significant impact on the development of international law and how the international legal order has developed and adjusted to accommodate the EU as a distinct legal actor. In doing so, it contributes to our understanding of how international law addresses legal subjects other than States.