Sovereignty is the subject of many debates in international relations. Is it the source of state authority or a description of it? What is its history? Is it strengthening or weakening? Is it changing, and how? This book addresses these questions, but focuses on one less frequently addressed: what makes state sovereignty possible? The Sovereignty Cartel argues that sovereignty is built on state collusion – states work together to privilege sovereignty in global politics, because they benefit from sovereignty's exclusivity. This book explores this collusive behavior in international law, international political economy, international security, and migration and citizenship. In all these areas, states accord rights to other states, regardless of relative power, relative wealth, or relative position. Sovereignty, as a (changing) set of property rights for which states collude, accounts for this behavior not as anomaly (as other theories would) but instead as fundamental to the sovereign states system.