But the Supreme Court has also long held that the Equal Protection Clause of the Fourteenth Amendment disfavors government practices (like admissions policies at public universities) that explicitly treat people differently based on which racial box they check. The same principle is embodied in Title VI of the 1964 Civil Rights Act, which applies to all universities (including private institutions) that receive public funding. Universities, the courts have held, can only use race when it is “necessary” to promote diversity.

The swing vote on the Supreme Court, Justice Anthony Kennedy, has been very skeptical that racial preferences are always required to produce racial diversity on campus. He has long sought to push universities to pursue alternative means to achieve diversity—such as giving a preference to economically disadvantaged students of all races, or admitting the top proportion of students from all high schools in a state.

Given Kennedy’s legal stance, affirmative-action policies at selective colleges are very vulnerable. Universities generally don’t use race as a last resort, and they weigh it very heavily in admissions decisions. Rather than reaching out to economically disadvantaged students of all races, today’s affirmative-action policies explicitly look at race and tend to advantage fairly well-off African American and Latino students to sit alongside their well-off white and Asian peers.

In the early days, affirmative action properly helped the young Sonia Sotomayor, who grew up in public housing, and the young Michelle Obama, whose parents did not go to college. But over time, the programs morphed into something very different. By the 1990s, one study found that 86 percent of African American students on selective campuses were middle or upper class, and the white students were even richer.

Underrepresented minority students receive a 28-percentage-point increase in their chances of being admitted, according to one careful analysis. By contrast, the study found low-income students receive no boost whatsoever. Not surprisingly, at selective colleges, one is 14 times as likely to run into a student from the richest quarter of the population as he or she is someone from the poorest quarter.

The Fisher case is an attractive vehicle for Justice Kennedy to take his stand. In the litigation to be heard by the Supreme Court, Abigail Fisher, a white student, has sued the University of Texas at Austin for using race in admissions and pointed out that alternative mechanisms used by Texas were effective in enrolling African American and Latino students, rendering racial preferences unnecessary.

The Texas story begins in 1996, when the Fifth Circuit Court of Appeals banned the use of race in admissions at UT Austin and other public institutions in Texas and nearby states in the case of Hopwood v. Texas. In response, Texas devised two alternatives for indirectly promoting racial diversity—providing a leg up to economically disadvantaged students of all races and admitting all students in the top 10 percent of every high-school class. Because Texas high schools are highly segregated, and because black and Latino students are disproportionately poor, the plans produced considerable racial and ethnic diversity.