After World War II, the United States championed the creation of an international order based on legal principles. In recent decades, enthusiasm for rules-based order has decreased dramatically-to the dismay of many around the world. This book provides a useful overview of Washington's ambivalent, shifting stance toward the international rule of law. Murphy does not offer a grand theory to explain growing U.S. resistance to international legal agreements. His emphasis is on the ambiguity of international law, its unsettled status under the U.S. Constitution, and the expansion in the range of issues brought into the international legal realm. Indeed, the United States' ambivalence is less new than is the dramatic increase in the scope of international law-driven by the globalization of the world economy and the externalization of such issues as criminal law, environmental regulation, and social and political rights. These insights emerge from detailed case studies of treaty disputes relating to topics such as the use of force, arms control, the International Court of Justice, and human rights. Missing from the book is a sense of the domestic and international politics of rules-based agreements or the impact of long-term shifts in the U.S. global position. In the end, Murphy hedges his bets by offering two future scenarios: one in which U.S. adherence to international law increases and another in which it continues to decline.