Abstract: The International Criminal Court (ICC) makes headlines around the world when it issues its occasional judgments. But most of the work of fighting impunity for severe crimes condemned by international law depends on national enforcement. Two separate efforts are currently underway to strengthen international cooperation in ensuring national prosecution: 1) a multi-year project of the International Law Commission (ILC) to draft articles for a future convention on the prevention and punishment of crimes against humanity, comparable to the existing Genocide Convention and Convention Against Torture; and 2) an episodic state-led initiative to draft a mutual legal assistance treaty for the most serious international crimes. The Human Rights Program at HLS recently convened a private workshop to discuss the vitally important ILC project.