Summary

International law is the set of rules, formally agreed by treaty or understood as customary, by which nation-states interact with each other in a form of international society. Across the history of U.S. foreign relations, international law has provided both an animating vision, or ideology, for various American projects of world order, and a practical tool for the advancement of U.S. power and interests. As the American role in the world changed since the late 18th century, so too did the role of international law in U.S. foreign policy. Initially, international law was a source of authority to which the weak American government could appeal on questions of independence, sovereignty, and neutrality. As U.S. power grew in the 19th and early 20th centuries, international law became variously a liberal project for the advancement of peace, a civilizational discourse for justifying violence and dispossession, and a bureaucratic and commercial tool for the expansion of empire. With the advent of formal inter-governmental organizations in the 20th century, the traditional American focus on neutrality faded, to be replaced by an emphasis on collective security. But as the process of decolonization diluted the strength of the United States and its allies in the parliamentary chambers of the world’s international organizations, Washington increasingly advanced its own interpretations of international law, and opted out of a number of international legal regimes. At the same time, Americans increasingly came to perceive of international law as a vehicle to advance the human rights of individuals over the sovereign rights of states.