Jus cogens are a species of supernorm in international law. They are universally binding and trump all contrary rules—such as treaties and customary international law. They are typically framed in terms of substantive prohibitions: no genocide, no slavery, no crimes against humanity, etc. This Article seeks to identify a procedural jus cogens; namely, the right to due process of law made up of notice, a hearing, and an impartial and independent decisionmaker. To do so, it draws from what are called “general principles of international law”; that is, principles common to legal systems around the world, which make up a source of international law. It argues that a comparative approach to these principles can reveal an empirically supported, objective underlying natural law right. In particular, by looking to rights states deem most important, hierarchically superior, and foundational to their legal systems as contained in their constitutions, this approach solves major seemingly intractable jurisprudential and practical dilemmas for the international law of jus cogens by providing an alternative to horizontal, consent-based positivistic law of treaties and custom.To make its argument it examines the 193 member states of the United Nations, plus Kosovo, the Republic of China (Taiwan), and the Vatican City (Holy See). Diligent research has revealed that virtually all states in the world secure the most basic requirements of due process: notice, a hearing, and an impartial and independent decisionmaker. More specifically, 189 states provide notice to the accused, 196 states provide for the right to a hearing, and 196 states provide for an impartial and independent decisionmaker. Moreover, the vast majority of these protections are constitutional. The right to notice is protected in 179 constitutions, the right to a hearing is protected in 193 constitutions, and the right to an impartial and independent decisionmaker is protected in 193 constitutions. This analysis easily satisfies the recent International Law Commission criteria that for a norm to qualify as jus cogens it must be accepted by “a very large majority of states . . . across regions, legal systems and cultures.”Discovering a procedural jus cogens would be revolutionary in some respects. A procedural jus cogens norm would expand the concept of jus cogens because such a norm would qualitatively differ from a substantive one since it is not merely a negative obligation on a state but imposes a positive duty to provide a right. Further, the Article’s argument holds powerful implications not just for international law but for domestic U.S. law as well. The Supreme Court long ago held that international law is part of our law, including the law of jus cogens, and mechanisms exist to enforce that law in U.S. courts
