In 1951, black radical William Patterson presented the United Nations with a petition, emblazoned with the title We Charge Genocide. The document charged the US government with snuffing out tens of thousands of black lives each year, through police violence and the systemic neglect of black citizens’ well-being. While historians have tended to discuss We Charge Genocide as a remarkable but brief episode, the petition built on prior attempts to invoke international law on behalf of African Americans and resonated with later generations of black activists whose political activism transcended more limited and domestic notions of civil rights. These later invocations of the genocide charge spanned the black left, including the Black Panther Party, the Student Non-Violent Coordinating Committee, James Baldwin and black feminists. This essay explores how the historical memory of racial violence, including settler colonialism and the slave trade, inspired an ideologically diverse array of organizations to each connect their experience to global histories of racial oppression. It stresses the internationalist and anticolonial perspective of the genocide charge and its proponents’ economic and transnational critique, thereby contributing to the historiographies of the long civil rights movement and black radicalism. By invoking international law, these black radicals connected the civil rights movement in the US to the struggle for human rights worldwide. Finally, the essay considers how integrating the local, national and global scales of racialized violence and its response enables historians to transnationalize the long civil rights movement paradigm.