AP Photo/Steven Senne Supreme Court Justice Sonia Sotomayor Y esterday, the Supreme Court upheld a provision of Michigan's constitution that bans the state or any of its subdivisions from "grant[ing] preferential treatment to any individual or group on the basis of race, sex, color, ethnicity, or national origin in the operation of public employment, public education, or public contracting." The Court was fractured; the six justices who voted to uphold the amendment did so for three independent reasons. Written by Justice Anthony Kennedy, the plurality decision—to which Chief Justice John Roberts and Associate Justice Samuel Alito signed on—was narrow: It upheld the amendment without disturbing any precedent. Far more interesting was Justice Sonia Sotomayor's dissent, which makes a strong case for a robust interpretation of the equal-protection clause of the 14th Amendment and represents perhaps her most compelling work in her tenure on the Court so far. The case for upholding...