The Trump Administration in July withdrew Obama-era guidance that gave colleges a wink and a nod to racially discriminate. This means that colleges like Harvard that use racial preferences in admissions will receive more legal scrutiny, and the examination should be instructive.

Between 2011 and 2016, the Obama Education Department issued seven notices advising colleges how they may legally promote racial diversity. The 1964 Civil Rights Act prohibits racial discrimination by institutions receiving federal funds. But the Supreme...