From its earliest decisions in the 1790s, the U.S. Supreme Court has used international law to help resolve major legal controversies. This book presents a comprehensive account of the Supreme Court's use of international law from the Court's inception to the present day. Addressing treaties, the direct application of customary international law, and the use of international law as an interpretive tool, the book examines all the cases or lines of cases in which international law has played a material role, showing how the Court's treatment of international law both changed and remained consistent over the period. Although there was substantial continuity in the Supreme Court's international law doctrine through the end of the nineteenth century, the past century was a time of tremendous doctrinal change. Few aspects of the Court's international law doctrine remain the same in the twenty-first century as they were two hundred years ago. This book presents a comprehensive account of the Supreme Court's use of international law from the Court's inception to the present day. David L. Sloss is Professor of Law at Santa Clara University School of Law, where he serves as Director of the Center for Global Law and Policy. He is the editor of The Role of Domestic Courts in Treaty Enforcement: A Comparative Study (2009). He has published numerous articles on the history of US foreign affairs law and the judicial enforcement of treaties in US courts. Michael D. Ramsey is Professor of Law at the University of San Diego School of Law. He is the author of The Constitution's Text in Foreign Affairs (2007) and of numerous articles examining the foreign affairs aspects of the US Constitution in the founding era. William S. Dodge is Professor of Law at the University of California, Hastings College of the Law. He is coauthor (with Detlev Vagts and Harold Koh) of Transnational Business Problems, 4th edition (2008) and has written extensively on the history of international law in American courts and on statutory interpretation in the international context.