Jennifer Gratz is a model of diversity. The daughter of a policeman and a secretary in Southfield, Mich., she was the first person in her family to apply to college, sporting a résumé that included a 3.8 grade point average, 25 ACT score, and membership in the National Honor Society and student council. She was class vice president. Yet she was denied admission to the University of Michigan because racial preferences stacked the deck against her and her white, Asian, Indian, and Jewish peers by granting 20 points to black or Latino students, on an 80-point scale; a perfect standardized...