Seizing the Grotian Moment: Accelerated Formation of Customary International Law in Times of Fundamental Change

Growing out of the author's experience as Special Assistant to the International Prosecutor of the Cambodia Genocide Tribunal in 2008, this article examines the concept of "Grotian Moment," a term the author uses to denote a paradigm-shifting development in which new rules and doctrines of customary international law emerge with unusual rapidity and acceptance. The article argues that the paradigm-shifting nature of the Nuremberg precedent, and the universal and unqualified endorsement of the Nuremberg Principles by the U.N. General Assembly in 1946, resulted in accelerated formation of customary international law, including the mode of international criminal responsibility now known as Joint Criminal Enterprise (JCE) liability. As such, the Cambodian Genocide Tribunal may properly apply JCE to crimes that occurred in 1975-1979, twenty years before the modern international tribunals recognized JCE as customary international law. The article uses this example to demonstrate the value of the "Grotian Moment" concept to explain an acceleration of the customary law-formation process and the heightened significance of certain General Assembly resolutions during times of fundamental change.