Purging the Odious Scourge of Atrocities explains the growth of a small body of human rights law that bans the use of violence against a state's own population when it is deemed a mass atrocity. These laws are binding on all states regardless of whether they have accepted it by signing treaties, or whether it is consistent with widespread state practice. Yet, this challenges the doctrine of consent, which has traditionally been the foundation of international law. Bruce Cronin argues that qualitative changes in the form of global governance are leading to an expansion in the theoretical underpinnings of international law and its role in contemporary world politics. Specifically, in limited and well-defined areas of international law, states have begun to recognize the authority of collective international consensus over individual state consent as the source of some legal rules.

Cronin supports this theory by examining the degree to which the international community has, via multilateral conferences among states, developed a consensus around the legal control of "excessive internal state violence"--that is, a level of coercive force that the international community considers to be disproportionate and illegitimate for pursuing state interests within its own borders. These practices, which the Genocide Convention refers to as an "odious scourge", include widespread, systematic attacks on civilian populations; violent persecution of defined groups (including genocide, ethnic cleansing, and apartheid); torture; and the violation of civilian immunity in internal armed conflicts. In these cases, state action is subject to general international law that overrides their consent. By allowing us to rethink the mechanisms that give international law actual force, Purging the Odious Scourge of Atrocities promises to reshape our understanding of why states are required to abide by human rights norms they never consented to by treaty or customary practice.