The orthodox view that states have no role in U.S. foreign relations is not only inconsistent with their place in the modern global economy, but the constitutional basis for a "dormant" bar on state participation - that is, absent a controlling federal statute or treaty - is obscure. Revisionist scholarship, and recent Supreme Court case law, suggest that Congress alone should decide when the states must stay out of foreign relations.
In this article, I argue that both the orthodox and revisionist views neglect an alternative basis for a judicial role - the Treaty Clause, enforced through the dormant treaty power. The text, structure, and original understanding of the treaty power establish two important principles of continuing validity. First, the President was to have an independent and substantive authority to negotiate on behalf of the United States, the better to secure advantageous treaties and avoid perilous entanglements. Second, state interference with this negotiating authority, even prior to the conclusive adoption of a federal treaty or statute, was unlawful.
Treaty Clause exclusivity is best maintained by a judicially-enforced dormant treaty power barring the states from bargaining with foreign powers, including indirect bargaining through measures that are contingent on foreign government policies - such as the Massachusetts law targeting companies doing business with Burma. However, state activities that incidentally have effects overseas would not be precluded, and the jurisprudence must be informed by the original rationales for federal exclusivity and by the President's discretion to exempt state activities posing no threat to federal functions.
Duke Law Journal, Vol. 49, March 2000