In December 2023, when South Africa accused Israel of genocide before the International Court of Justice, I thought it was wrong to do so. Israel had been attacked. Its defense was legitimate. The blood was on Hamas’s hands. But over the last year, I have watched a slew of organizations and scholars arrive at the view that whatever Israel’s war on Gaza began as, its mass assault on Palestinian civilians fits the definition of genocidal violence. This is a view now held by Amnesty International, B’Tselem, Human Rights Watch, and the president of the International Association of Genocide Scholars, among many others One reason I have stayed away from the word genocide is that there is an imprecision at its heart. When people use the word genocide, I think they imagine something like the Holocaust: the attempted extermination of an entire people. But the legal definition of genocide encompasses much more than that. So what is a genocide? And is this one? Philippe Sands is a lawyer who’s worked on a number of genocide cases. He is the author of, among other books, “East West Street,” about how the idea of genocide was developed and written into international law. He is the best possible guide to the hardest possible topic. Mentioned: “What the Inventor of the Word ‘Genocide’ Might Have Said About Putin’s War” by Philippe Sands “‘Only the Strong Survive.’ How Israel’s Benjamin Netanyahu Is Testing the Limits of Power” by Brian Bennett “The laws of war must guide Israel’s response to Hamas atrocity” The Ratline by Philippe Sands 38 Londres Street by Philippe Sands Book Recommendations: Janet Flanner’s World by Janet Flanner Commonwealth by Ann Patchett By Night in Chile by Roberto Bolaño Thoughts? Guest suggestions? Email us at ezrakleinshow@nytimes.com. You can find the transcript and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast. Book recommendations from all our guests are listed at https://www.nytimes.com/article/ezra-klein-show-book-recs.html This episode of “The Ezra Klein Show” was produced by Jack McCordick and Annie Galvin. Fact-checking by Michelle Harris, with Kate Sinclair. Our senior engineer is Jeff Geld, with additional mixing by Aman Sahota. Our executive producer is Claire Gordon. The show’s production team also includes Marie Cascione, Annie Galvin, Rollin Hu, Elias Isquith, Kristin Lin, Marina King and Jan Kobal. Original music by Marian Lozano, Dan Powell, Carole Sabouraud and Pat McCusker. Audience strategy by Kristina Samulewski and Shannon Busta. The director of New York Times Opinion Audio is Annie-Rose Strasser. Unlock full access to New York Times podcasts and explore everything from politics to pop culture. Subscribe today at nytimes.com/podcasts or on Apple Podcasts and Spotify.