One of the old axioms of international relations is that might makes right. But in fact, even powerful states seek to legitimate their actions by invoking the authority of international law and institutions. Scholars do not fully understand the sources of legitimacy in world affairs or how it shapes and constrains what leaders do, but this book provides important insights by looking closely at one particular site of international authority: the United Nations Security Council. Hurd argues that the Security Council is not just a "talk shop"; it wields authority because it represents the "collective sentiment" of the international community. Hurd traces the Security Council's authority to its World War II founding, its universalism, and, critically, its "proceduralism." Most of the book is concerned with identifying the ways that states react to this wellspring of global authority. Unfortunately, Hurd does not address the debate about alternatives to the council's authority, but the implication of his argument is that less universal bodies will have a hard time rivaling its symbolic, moral, and legal stature.