The International Committee of the Red Cross Regional Delegation for the United States and Canada, the Harvard Law School Program on International Law and Armed Conflict, and the Stockton Center for the Study of International Law at the U.S. Naval War College recently hosted a workshop titled Global Battlefields: The Future of U.S. Detention under International Law. The workshop was designed to facilitate discussion on international law issues pertaining to U.S. detention practices and policies in armed conflict. Workshop participants included members of government, legal experts, practitioners and scholars from a variety of countries. This report attempts to capture the main debates that arose in each session.