The Process of International Law-Making: The Relationship between the International Court of Justice and the International Law Commission

Abstract

Article 38, para.1, of the Statute of the International Court of Justice (“ICJ”) defines customary international law as evidence of general practice accepted as law, understood as State practice and opinio juris. However, by identifying certain norms as custom without referring to the traditional evidence of State practice and opinio juris, international courts and tribunals have also contributed to the formation of customary international law. This paper presents an analysis of how the ICJ in particular, contributes to the formation of customary international law by relying on the draft articles of the International Law Commission (“ILC”).

The paper is based on two premises: the ICJ through its functions in applying international law (art.38 ICJ Statute, para.1) creates international law, by clarifying and identifying international law; whereas the ILC, by adopting on draft articles created in a creative process, directly contributes to the creation of international law unless States adopt the ILC draft articles in a treaty. By relying on the un-adopted ILC draft articles and declaring them to be customary international law, the ICJ creates and generates customary international law.

The ICJ has been referring to the ILC draft articles since the 1969 North Sea Continental Shelf Case, and has over the years declared the draft articles to be customary international law. Interestingly, the ICJ tends to rely only on particular ILC draft articles that refer to the jurisprudence of either the Permanent Court of International Justice (“PCIJ”) or the ICJ itself. The paper presents research on 70 ICJ decisions and opinions of individual judges that cite to the work of the ILC. The author notes the evolution of the ICJ-ILC relationship through three different time periods, and presents the findings on how, when and why the ICJ relies on the ILC draft articles. In addition, the author gives examples in which the ICJ rejected the reliance on the ILC’s work, mainly due to the divergent interpretation on the specific topic of international law.

The ICJ, by relying on the ILC draft work as an international legislative tool or evidence of customary international law, is not only generating norms of customary international law, but is also re-affirming the importance of its (and PCIJ’s) jurisprudence for the future of international law. Although ICJ decisions are binding only between the parties to the dispute (Art.59 ICJ Statute), the clarification of whether a norm is customary or not, affects the international community of States. Noting the reluctance of States to adopt treaties, and hence their potentially decreasing role in international law-making, this research offers an insight into an alternative venue of international law-making. As the international community, and the ILC itself, is shifting focus on the sources of international law, this paper aims to identify the mechanisms behind international law-making, which will ultimately contribute to international law’s needed predictability and a more uniform and reliable interpretation of international law.

Keywords: International Court of Justice, International Law Commission, international law-making, customary international law, relationship between the International Court of Justice and the International Law Commission, judicial law-making