Codification 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.

The article discusses the question of the international responsibility of the European Community against the background of the International Law Commission's (ILC) recent work on the responsibility of international organizations generally. It describes the role of the EC (and EU) in international relations and highlights its special legal features in the light of plentiful practical examples. The various practical issues drawn from the EC's voluminous international treaty practice are grouped into what the paper calls “horizontal” and “vertical” issues, illustrating the different aspects related to the division of competence between the organization and its Member States and the operating features of the EC legal system reflecting its nature as “executive federalism”. The underlying theme of the paper recognizes that there are important “public morals” aspects calling for clear rules on the responsibility of international organizations, but there are also practical realities related to the diversity of international organizations pointing to the direction of special rules for instance in the case of the EC. On the basis of a broad review of the EC practice, the paper offers some critical comments on the ILC work suggesting that the traditional notion of an international organization does not resonate well with the realities of the European Community. In particular it argues that the ILC has overlooked the notions such as the Regional Economic Integration Organization (REIO), which has emerged in multilateral treaty practice during recent years, and failed to consider broader international law implications that such practice entails, including for purposes of international responsibility.