118 Yale L.J. 1762 (2009). 

What is the force of international law as a matter of U.S. law? Who determines that force? This Essay maintains that, for the United States, the U.S. Constitution is always supreme over international law. To the extent that the regime of international law yields determinate commands in conflict with the Constitution’s commands or assignments of power, international law is, precisely to that extent, unconstitutional. Further, the force of treaties (and executive agreements) to which the United States is a party is always subject to the constitutional powers of Congress and the President to supersede or override them as a matter of U.S. domestic law. It follows from the Constitution’s allocation of power exclusively to U.S. constitutional actors that the power to interpret, apply, enforce—or disregard—international law, for the United States, is a U.S. constitutional power not properly subject to external direction and control. The power “to say what the law is,” including the power to determine the content and force of international law for the United States, is a power distributed and shared among the three branches of the U.S. government. It is not a power of international bodies or tribunals. This understanding of the relationship of international law to the U.S. Constitution’s allocation of powers in matters of war and foreign affairs has important implications for many contemporary issues and the United States’s actions with respect to compliance with international treaties and other international law norms in the areas of criminal law enforcement, the conduct of war, war prisoner detention and interrogation practices, and the imposition of military punishment on unprivileged enemy combatants.