For nearly two centuries, all three branches of the federal government have thought that the original meaning of the Constitution’s references to treaties and compacts was lost. This Article aims to recover those original meanings by looking to an under-examined source—the contemporary law of nations. In 1787, that body of law regarded compacts, rather than treaties, as the umbrella category for all international agreements. Treaties—defined as executory commitments among sovereigns only—were but one form of compact. Others included executed “conventions,” agreements by “subsidiary powers,” and unauthorized “sponsions.” Each category had a specialized meaning—they were terms of art—in both the scholarly corpus that delimited the field and contemporary practice.
Although neither dictionaries nor the Framing materials explicitly invoke these definitions to assign constitutional meaning, there is extensive evidence in the constitutional text, intellectual history, and early U.S. practice for doing so. I identify support for a law of nations thesis in an array of previously ignored agreements, including those made by George Washington and Benedict Arnold. A law of nations thesis also helps explain why the United States concluded certain agreements as treaties and others as conventions in its earliest years.
This Article thus provides a new and historically rooted foundation for U.S. foreign relations law, with important implications for the scope and exclusivity of the Treaty power, the power to conclude “executive agreements,” the doctrine of non-self-executing treaties, the ban on U.S. state treaty-making, and the Constitution’s authorization of compacts with congressional consent.