International Organizations and the Creation of Customary International Law

Abstract This article argues that international organizations ‘as such’ can contribute directly to the creation of customary international law for three independent reasons. First, the states establishing an international organization may subjectively intend for that organization to be able to contribute to the creation of at least some kinds of customary international law. Second, that capacity may be an implied power of the organization. Third, that capacity may be a byproduct of other features or authorities of the international organization – specifically, the combination of international legal personality and the capacity to operate on the international plane. Affirming international organizations’ direct role in making customary international law will not dramatically change the content of customary international law or the processes by which rules of customary international law are ascertained. But recognizing that role is significant because it will reinforce other conclusions about how international organizations fit into the international legal system, including that customary international law binds international organizations. Such recognition may also shift the way lawyers within international organizations carry out their work by affecting the sources they consult when answering legal questions, the materials they make publicly available and the kinds of expertise that are understood to be necessary to discharge their responsibilities. Finally, affirming international organizations’ role in creating customary international law may make international organizations more willing to comply with those rules.