The number of peremptory norms is considered limited but not exclusively catalogued. Included are prohibitions on waging aggressive war, piracy, genocide, slavery, and torture.
Despite the seemingly clear weight of condemnation of such practices, some critics disagree with the division of international legal norms into a hierarchy. There is also disagreement over how such norms are recognized or established. The relatively new concept of peremptory norms is at odds with the traditionally consensual nature of international law considered necessary to state sovereignty. However, sovereignty has never truly been an absolute concept and limitations upon it are increasingly supported.