Customary International Law, Change, and the Constitution

Abstract

Customary international law has changed in many ways since ratification of the U.S. Constitution. This Article considers the implications of those changes for customary international law’s role under the Constitution. In particular, it challenges the claims made in a new book, The Law of Nations and the United States Constitution, that U.S. courts must respect the “traditional rights” of foreign nations under the law of nations and may not apply the modern customary international law of human rights. This Article argues that the book is inconsistent in its approach to changes in customary international law, embracing some but rejecting others. This Article also shows that a full account of the changes in customary international law undercuts the book’s two constitutional arguments.

Keywords: customary international law, law of nations, human rights, vattel