REFLECTIONS OF CUSTOMARY INTERNATIONAL LAW: THE AUTHORITY OF CODIFICATION CONVENTIONS AND ILC DRAFT ARTICLES IN INTERNATIONAL LAW

Abstract

AbstractCodification conventions and draft articles completed by the International Law Commission are often—and increasingly—invoked by courts, tribunals, governments and international organizations as ‘reflections of customary international law’. This article discusses the factors explaining the authority that these ‘non-legislative codifications’ have come to enjoy in international legal reasoning. Moving beyond the traditional explanations of codification conventions as evidence of State practice and ILC draft articles as the teaching of publicists, it considers how, against the backdrop of the uncertainty of customary international law, institutional factors (relating to authorship, representation and procedure) and textual factors (including prescriptive form and the absence of a distinction between ‘codification’ and ‘progressive development’) converge to convey the image that the resulting texts constitute the most authoritative restatement of the existing law. It then assesses this phenomenon in light of the political ideal of the international rule of law. While non-legislative codifications contribute to enhancing the clarity, consistency and congruence of international law, the fact that they may portray novel rules as reflecting existing law inevitably raises legality concerns.