The Supremacy Clause as Structural Safeguard of Federalism: State Judges and International Law in the Post-Erie Era

Abstract

Against a backdrop of state constitutional and legislative initiatives aimed at limiting judicial use of international law, this Article argues that state judges have, by and large, interpreted treaties and customary international law so as to narrow their effect on state law-making prerogatives. Where state judges have used international law more liberally, they have done so to give effect to state executive and legislative objectives. Not only does this thesis suggest that the trend among state legislatures to limit state judges’ use of international law is self-defeating, it also gives substance to a relatively unexplored structural safeguard of federalism: state judges’ authority under the Supremacy Clause to harmonize treaties and customary international law with state constitutional, legislative, and common law, and to influence federal jurisprudence on the scope and effect of binding international law. The Supremacy Clause empowers state judges to adapt international law to maximize benefits for - and minimize disruptions to - state policy objectives. As more areas of traditional state authority are displaced by international law, state judicial management of international law may be the strongest structural protection for state interests.