Confirming and Contesting International Law The European Union and the United Nations International Law Commission

How has the European Union (EU) engaged with the work of the United Nations (UN) International Law Commission (ILC) and what does this engagement tell us about the EU’s understanding of its relationship with, and contribution to, public international law? This thesis answers this question. In doing so, it offers the first systematic analysis of all the statements prepared by the EU and delivered at the UN General Assembly’s Sixth Committee (Legal) concerning ILC annual reports, from 1975 to 2021. Combining doctrinal and empirical research, this work shows how the EU’s engagement with the ILC has evolved into an established practice of dialogue between EU and international lawyers, led by the Legal Service of the European Commission. The thesis brings together EU statements on eleven distinct topics of public international law studied by the ILC in the last fifty years, clustering them around three themes: the law of treaties, the responsibility of international organisations, and substantive areas of international law. Through the framing concepts of contestation and confirmation, this research demonstrates how the claim that EU practices contribute to the (trans)formation of international law has been made by EU lawyers. In doing so, it uncovers a story about the EU’s understanding of its contribution to distinct areas of public international law and sheds light on the role that EU autonomy has played in this context. The research findings are therefore of interest to both EU and international law scholars.