'Purging the Odious Scourge of Atrocities' explains the growth of a small body of human rights law that is binding on all states regardless of whether they have accepted it by signing treaties or whether it is consistent with widespread state practice. This challenges the doctrine of consent, which has been the foundation of international law for the past several centuries. The book argues that qualitative changes in the form of global governance are leading to an expansion in the underpinnings of international law and its role in contemporary world politics.