The identification of Customary International Law: a process that defies prescription

Abstract

The subject of identification of customary international law (CIL) has been under consideration by the United Nations International Law Commission (ILC) since 2012, evoking responses from States and scholars. The ILC has finalized in its second and final reading a set of 16 conclusions.I discuss these conclusions in the light of the well-established doctrine on the formation of CIL. I disucss the “two elements” approach – general practice and its acceptance as law – and offer guidance on capturing the moment of creation of CIL, focusing on relevant factors, in particular the temporal factor. I emphasise the role power, persuasion, consensus, common interests or commonly shared community policies play in the formation of CIL, while noting various forms of practice including the United Nations General Assembly resolutions as important indicators for this purpose. I find many of the conclusions adopted by the Commission well balanced and in consonance with the well-established principles governing the formation of customary international law. Mention may be made in this connection of the conclusion that the practice of international organizations in certain cases also constitutes relevant practice, even as it is clear that it is State practice that predominantly figures in the evolution of “general practice”. It is, however, felt that the principle of persistent objector and that the concept of “specially affected States” has no real basis in practice and are otherwise best accommodated by other well-known principles of international law, such as acquiescence or estoppel or historic rights.