LAUSR

Abstract In his Fourth Report on the Identification of Customary International Law (2016), Special Rapporteur Sir Michael Wood confirmed that ‘[i]n certain cases, the practice of international organizations also contributes to the expression, or creation, of rules of customary international law’. That the practice of international organizations can be relevant when identifying customary international law is relatively uncontroversial. The issue that is more debated is the extent to which the practice of international organizations as such may contribute to the development of customary international law. Using examples from the European Union's treaty practice and from the Court of Justice of the European Union, this article argues that international organizations may contribute to such practice, not only by representing the collective will of States, but as autonomous actors in their own right.