Commentary The Supreme Court’s decision to hear challenges to affirmative action policies at Harvard and the University of North Carolina (UNC) is welcome news for those of us who have fought for a quarter of a century to end race-based preferences in college admissions. At issue isn’t merely the admissions practices of two prestigious universities, one private and the other public, but the larger question of whether racial preferences are a legitimate way to promote diversity in higher education. I tackled this very issue in my first book, “Illiberal Education,” published in 1991. In that book, I did an in-depth study of admissions practices at the University of California–Berkeley. I asked the admissions director there to consider a student with near-perfect grades, standardized test scores in the 90th percentile, and very good extracurricular talents. If such a student were black or Hispanic, I asked, what’s the chance that he (or …