Never again. When the United Nations was originally founded from the ashes of the second world war, it was at least in part to give more solid meaning to those words. The first treaty it ever adopted, thanks to the efforts of a Polish Jew named Raphael Lemkin who had lost more than 40 members of his family in the Holocaust, was the convention on the prevention and punishment of the crime of genocide. From Rwanda to Srebrenica, the UN itself admits it hasn’t always lived up to Lemkin’s ideals. Its founding mission remains, however, to learn from history, not...