The Supreme Court ruled 53 years ago in Brown v. Board of Education that segregated education is inherently unequal, and it ordered the nation’s schools to integrate. Yesterday, the court switched sides and told two cities that they cannot take modest steps to bring public school students of different races together. It was a sad day for the court and for the ideal of racial equality.

Since 1954, the Supreme Court has been the nation’s driving force for integration. Its orders required segregated buses and public buildings, parks and playgrounds to open up to all Americans. It wasn’t always easy: governors, senators and angry mobs talked of massive resistance. But the court never wavered, and in many of the most important cases it spoke unanimously.

Yesterday, the court’s radical new majority turned its back on that proud tradition in a 5-4 ruling, written by Chief Justice John Roberts. It has been some time since the court, which has grown more conservative by the year, did much to compel local governments to promote racial integration. But now it is moving in reverse, broadly ordering the public schools to become more segregated.

Justice Anthony Kennedy, who provided the majority’s fifth vote, reined in the ruling somewhat by signing only part of the majority opinion and writing separately to underscore that some limited programs that take race into account are still acceptable. But it is unclear how much room his analysis will leave, in practice, for school districts to promote integration. His unwillingness to uphold Seattle’s and Louisville’s relatively modest plans is certainly a discouraging sign.