Sunday marks 25 years since the U.S. Senate ratified the United Nations Convention on the Prevention and Punishment of the Crime of Genocide. That convention entered into force in 1951 but the U.S. Senate refrained from ratification until 1986. Why? Adam Jones is a professor of political science at the University of British Columbia and author of “Genocide: A Comprehensive Introduction.” Jones says the U.S. delayed ratification of the convention because, in part, of fears that U.S. treatment of African Americans and Native Americans might open it up to accusations of genocide.