(Meta) Grotian Moment: International Organizations and the Rapid Formation of Customary International Law

In this paper, I first discuss the concept of ‘Grotian Moment’ in the context of the capacity of international organizations to contribute to the formation and identification of customary international law. Afterward, I apply three levels to discuss the time element of the formation of custom. At the micro-level of the institutional practice, the time required to form a customary norm may depend on whether each form of practice is directed to the institutional or to the international dimension. At the level of the organ, I reflect on the difference played by the presence or absence of member States in the institutional organ that adopts the practice relevant for custom formation. At the macro-level of the characteristics of the organization, I distinguish between so-called supranational and functional organizations. In general, I exclude the relevance of speaking in terms of a ‘Moment’ that produces a paradigm shift, and I stress the continuous change to which international law is subject.