International Organizations and the Creation of Customary International Law
European Journal of International Law, Volume 31, Issue 1, February 2020, Pages 201–233
33 Pages Posted: 13 Apr 2018 Last revised: 18 Oct 2021
Date Written: April 10, 2018
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 customary international law. Second, the capacity to contribute to at least some kinds of customary international law may be an implied power of the organization. Third, the capacity to contribute to at least some kinds of customary international law is a necessary incident of other features or authorities of international organizations — specifically the combination of international legal personality and the capacity to operate on the international plane.
Recognizing international organizations' direct role in making customary international law is unlikely to result in a dramatic shift in the content of customary international law or in the processes by which particular rules of customary international law are ascertained. The circumstances in which international organizations can contribute directly are fairly discrete and limited. That is not to say, however, that international organizations’ capacity to contribute directly to making customary international law does not matter. Instead, this conclusion matters primarily because it reinforces other conclusions about how international organizations fit into the international legal system. As a theoretical matter, recognizing that international organizations directly contribute to the formation of customary international law reinforces the conclusions that customary international law binds international organizations and that international organizations incur international responsibility when they violate international law. Both are important components for assuring the accountability of international organizations. As a practical matter, acknowledging that international organizations can contribute to the formation of customary international law may also have important consequences for how IO lawyers understand and carry out their work.
Keywords: international law, international organizations, international institutions, customary international law, International Law Commission
JEL Classification: K33
Suggested Citation: Suggested Citation