The High Representative of the Union for Foreign Affairs and Security Policy conducts the EU’s foreign policy and coordinates external relations within the European Commission. The present volume informs about his/her new role before the European Court of Justice and related case law. It also analyses the EU’s role in various classical fields of international law, such as litigating in the International Court of Justice, negotiating new rules on crimes against humanity, business and human rights or establishing a special tribunal on aggression against Ukraine. The rich contributions may help EU external relations and public international lawyers to construct their own analytical frameworks.