Ratko Mladić’s death last week at eighty-three in The Hague—where he was serving a life sentence for committing war crimes, crimes against humanity, and genocide as the commander of the Bosnian Serb forces during the war in Bosnia from 1992 to 1995—is a reminder that the International Criminal Tribunal for the former Yugoslavia was the most effective instrument the international community has devised since the tribunal at Nuremberg to hold accountable those responsible for great crimes. Indeed, in certain respects it went beyond the precedent that Nuremberg set. Where that tribunal had brought to justice only defendants from a defeated nation, the ICTY tried, convicted, and sentenced perpetrators from all parties to the conflicts that took place across the former Yugoslavia between 1991 and 1999. When the war in Bosnia began in April 1992, I was the director of Human Rights Watch. In late July, HRW released a book-length report documenting the crimes committed in the first four months of the conflict. We also proposed the creation of an international tribunal—the first time we had …