In 1978, Justice Powell famously found that racial diversity can justify race-conscious admissions systems. However, Justice Powell wrote alone, leaving the diversity rationale in a state of limbo for nearly three decades. In 2003, a slim majority of the Supreme Court agreed with Justice Powell, finding that an educational institution had a compelling interest in a diverse student body.

To buttress the idea that "educational benefits . . . flow from an ethnically diverse student body,"Justice Powell included a quote from a former Princeton graduate observing: "People do not learn very much when they are surrounded only by the likes of themselves." With this anecdotal support, the diversity rationale gained recognition in the Supreme Court...