Just needed to say that.

In a decision of sweeping importance to educators, parents and schoolchildren across the country, the Supreme Court today sharply limited the ability of school districts to manage the racial makeup of the student bodies in their schools. Skip to next paragraph The New York Times

Multimedia Interactive: Notable Cases of the 2006-7 Term Graphic Notable Cases of the 2006-7 Term: Affirmative Action

A look at notable cases of the term including the one that the ability of school districts to manage the racial makeup of the student bodies in their schools. With audio from some of the court’s arguments. Go » Related Opinion: Parents Involved v. Seattle School Dist. No. 1 Left, Bradley C. Bower/Reuters; right, Nick Ut/Associated Press

Chief Justice John Roberts, right, wrote the majority’s decision. Justice Stephen Breyer wrote the dissent.

The court voted, 5 to 4, to reject diversity plans from Seattle and Louisville, Ky., declaring that the districts had failed to meet “their heavy burden” of justifying “the extreme means they have chosen — discriminating among individual students based on race by relying upon racial classifications in making school assignments,” as Chief Justice John G. Roberts Jr. wrote for the court.

Today’s decision, one of the most important in years on the issue of race and education, need not entirely eliminate race as a factor in assigning students to different schools, Justice Anthony M. Kennedy wrote in a separate opinion. But it will surely prompt many districts to review and perhaps revise programs they already have in place, or go back to the drawing boards in designing plans.

In the hours after the ruling, reaction varied greatly, with some groups denouncing it as virtually inviting a return to the days of segregation, and others asserting that it need not be seen that way, in view of Justice Kennedy’s unwillingness to fully embrace Chief Justice Roberts’s opinion.

The rationale of the chief justice’s opinion relied in part on the historic 1954 decision in Brown v. Board of Education that outlawed segregation in public schools — a factor that the dissenters on the court found to be a cruel irony, and which they objected to in emotional terms.

Chief Justice Roberts said the officials in Seattle and in Jefferson County, Ky., which includes Louisville, had failed to show that their plans considered race in the context of a larger educational concept, and therefore did not pass muster.

“In the present cases,” Chief Justice Roberts wrote, recalling words from an earlier Supreme Court ruling, “race is not considered as part of a broader effort to achieve ‘exposure to widely diverse people, cultures, ideas, and viewpoints.’ ”

“Even as to race,” he went on, “the plans here employ only a limited notion of diversity, viewing race exclusively in white/nonwhite terms in Seattle and black/other terms in Jefferson County.

“Classifying and assigning schoolchildren according to a binary conception of race is an extreme approach in light of this court’s precedents and the nation’s history of using race in public schools, and requires more than such an amorphous end to justify it.”

“The way to stop discrimination on the basis of race is to stop discrimination on the basis of race,” Chief Justice Roberts wrote.

In a now-familiar lineup, Justices Kennedy, Antonin Scalia, Clarence Thomas and Samuel A. Alito Jr. sided with the chief justice on most points. (Justice Thomas wrote separately to say that the use of race alone for supposedly “benign” purposes must be avoided, just as the Brown decision said it could not be used for purely discriminatory purposes.)

Chief Justice Roberts wrote that rather than working toward a level of diversity and its “purported benefits,” the schools had “worked backwards to achieve a particular type of racial balance.”

“This is a fatal flaw,” the ruling said. “When it comes to using race to assign children to schools, history will be heard.”

The four dissenters wrote, in effect, that the majority was standing history on its head. Justice Stephen G. Breyer said that today’s result “threatens to substitute for present calm a disruptive round of race-related litigation, and it undermines Brown’s promise of integrated primary and secondary education that local communities have sought to make a reality.”

“This cannot be justified in the name of the Equal Protection Clause,” Justice Breyer went on, alluding to the Fourteenth Amendment to the Constitution, which bars states from denying people “the equal protection of the laws.”

Today’s ruling threatens the promise laid out in the 1954 Brown decision, Justice Breyer lamented. “This is a decision that the court and the nation will come to regret,” he wrote.

Justice Breyer’s dissent was joined by Justices David H. Souter, Ruth Bader Ginsburg and John Paul Stevens, the tribunal’s longest-serving member, who wrote a separate dissent that was remarkable for its feeling.

“While I join Justice Breyer’s eloquent and unanswerable dissent in its entirety, it is appropriate to add these words,” Justice Stevens wrote. “There is a cruel irony in the chief justice’s reliance on our decision in Brown vs. Board of Education.”

Today’s ruling breaks faith with the 1954 ruling, Justice Stevens asserted. “It is my firm conviction that no member of the court that I joined in 1975 would have agreed with today’s decision,” he wrote.

Justice Kennedy’s opinion concurring in part with Chief Justice Roberts, and with the overall judgment, agreed that the Seattle and Louisville plans went too far. However, in language that some people on the losing side found heartening, he said that race may still be a component of plans to achieve diversity in the schools.

“Diversity, depending on its meaning and definition, is a compelling educational goal a school district may pursue,” he wrote.

But Mark Rahdert, a Temple Law School professor and a former clerk to Supreme Court Justice Harry A. Blackmun, said that today’s ruling means that “racial balance” will be “the new catchphrase conservatives will use to attempt to eradicate any form of affirmative action.”

As for Justice Kennedy’s “willingness to leave the door open to some forms of affirmative action,” it will be impossible as a practical matter, Mr. Rahdert said.

The National Urban League issued a statement asserting that today’s decision “could end up legalizing re-segregation nationwide by raising the bar for achieving racial diversity.”

The decision today, in Parents Involved in Community Schools v. Seattle School District, No. 05-908, and Meredith v. Jefferson County Board of Education, No. 05-915, runs to some 180 pages, including the dissents. It was eagerly awaited by the National School Boards Association and by the Council of the Great City Schools, representing 66 urban districts, which had filed briefs on behalf of Seattle and Louisville and had warned of disruption if the justices overturned lower court rulings upholding the diversity plans.

The Bush administration participated as a “friend of the court” on behalf of the plaintiffs who challenged the diversity plans.

One plaintiff was a white woman in Louisville whose son was denied a transfer to attend kindergarten in a school that needed more black pupils to keep its black population at the district’s required minimum of 15 percent.

The other plaintiffs were Seattle parents who opposed the district’s “tiebreaker” system, which applies only to the city’s 10 high schools and is aimed at keeping the nonwhite proportion of their student bodies within 15 percentage points of the district’s overall makeup, which is 60 percent nonwhite.

Harry Korrell, lead attorney for the plaintiff-parents in Seattle, said his clients were “very pleased” with today’s decision. “This case was about protecting all children — regardless of skin color — from race discrimination,” he said.

Unlike the Seattle district, the Jefferson County school system was once segregated by law. Its current diversity plan was adopted in 2000, after the district emerged from 25 years of federal court supervision.