The Genocide Convention, drafted by the United Nations soon after the Nuremberg trials, represented a significant step toward the establishment of a regime of individual accountability for violations of international law. The Convention compels its signatories to prevent and punish certain enumerated acts committed with the intent to destroy, in whole or in part, a national, ethnic, religious, or racial group. Even though the Khmer Rouge era is widely considered a paradigmatic case of genocide, this article takes as its premise that much of the violence in Cambodia during the Khmer Rouge era (1975-78), in which almost a fifth of the population was executed or killed by being worked or starved to death, may not constitute genocide according to the strict definition of the offence contained in the Convention. This is because the Genocide Convention, unlike other international legal instruments, limits the protected classes to national, ethnic, racial, and religious groups. As such, the Extraordinary Chambers in the Courts of Cambodia (ECCC) may rule that the definition of genocide does not cover a significant portion of the deaths in Cambodia. This example illustrates a critical shortfall of the Genocide Convention.After protracted debate, the drafters of the Genocide Convention expressly excluded from Article II. An examination of the travaux preparatoires of the Convention reveals the compromises - born of politics and the desire to insulate political leaders from scrutiny and liability - that can occur when political bodies attempt to reduce customary law principles to positivistic expression. The exclusion of political groups from the Genocide Convention represents one such compromise. This Article argues that no legal principle can justify this blind spot. The Article also suggests that the Genocide Convention may not be the sole authority on the crime of genocide. Rather, a higher law exists: The prohibition of genocide represents the paradigmatic jus cogens norm, a customary and peremptory norm of international law from which no derogation is permitted. The jus cogens prohibition of genocide, as expressed in a variety of sources, may be broader than the Convention's prohibition, as has been demonstrated with respect to the jurisdictional principles applied to acts of genocide. Notwithstanding that the framers of the Genocide Convention attempted to limit the prohibition of genocide by deliberately excluding political groups from Article II, this provision is without legal force to the extent that it is inconsistent with the jus cogens prohibition of genocide. Therefore, when faced with mass killings evidencing the intent to eradicate political groups in whole or in part, domestic and international adjudicatory bodies should apply the jus cogens prohibition of genocide and invoke the Genocide Convention vis-a-vis signatories only insofar as it provides practical procedures for enforcement and ratification. As an overarching theme, this Article discusses the multiplicity of sources in international law and they way in which treaty and customary law rules diverge and interact over time.