The Supreme Court: Wide-Open Housing

In the "Reconstruction" that followed the Civil War, the victorious North tried to wipe out every lingering trace of slavery. But three constitutional amendments and more than half a dozen federal statutes could not put an end to prejudice. As Abolitionist Frederick Douglass wrote in 1881: "The colored man is the Jean Valjean of America. He has escaped from the galleys and hence all presumptions are against him."

Still, the liberating laws were there—largely unavailing and unenforced, but there. Last week the Supreme Court reached back across more than 100 years to use one of them to impose a major new...