WASHINGTON, D.C. — A week ago, I pondered whether public-school integration was dead. I got my answer Monday as I sat in the audience listening as the nine justices of the U.S. Supreme Court probed and prodded on the matter of race. Diversity, as a tool of public education, is dead as a doornail. It was in the air. The elegantly gilded courtroom turned somber as one justice after another dismissed the notion of purposeful diversity efforts in public education. Someone next to me whispered they had just seen the widow of former Supreme Court Justice Thurgood Marshall. As a...