The Supreme Court's conservative majority flexed its muscles Thursday by dismantling a key plank of "affirmative action" programs that promote racial diversity in US schools.
Provoking outrage from Democrats and civil-rights campaigners, the nation's highest court found that school authorities cannot use race alone in deciding the mix of their student populations.
By five to four, the justices ruled in favor of white parents whose children were denied places at their nearest schools in Seattle, Washington, and the Kentucky city of Louisville because of such admission policies.
"Simply because the school districts may seek a worthy goal doesn't mean that they are free to discriminate on the basis of race to achieve it," Chief Justice John Roberts wrote in the majority decision.
The decision could affect hundreds of US districts that try to give preference to black and other ethnic-minority children, if a school is over-subscribed and is deemed to have enough white children already.
Senate Majority leader Harry Reid said the ruling was "appalling," turning a landmark anti-segregation ruling of the 1950s "upside down."
"If this isn't judicial activism, I don't know what is," he said, reflecting Democratic suspicion of a court that, under President George W. Bush, has tilted markedly to the right.
Brenda Wright, legal director for the voting rights organization Demos, said ethnic-minority children in poorer areas would be condemned to languish in depressed schools.
The "narrow Supreme Court majority has done a grave disservice not just to educational equity but to our democracy as a whole," she said.
But backed by the Bush administration, the aggrieved parents argued that the admission policies were just as discriminatory as the racial segregation long enforced in southern schools after the abolition of slavery.
That segregation was struck down in the Supreme Court's "Brown v. Board of Education" ruling of 1954, a watershed moment in the historic civil rights movement.
In dissenting opinions, members of the court's liberal minority expressed their passionate disapproval of Thursday's ruling.
"This is a decision that the court and the nation will come to regret," justice Stephen Breyer wrote.
"The last half-century has witnessed great strides toward racial equality, but we have not yet realized the promise of 'Brown.'"
The court's longest-serving justice, John Paul Stevens, accused his conservative colleagues of standing history on its head.
"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.
In 2003, the Supreme Court narrowly upheld race-based admissions policies at the University of Michigan Law School, but said that race must be only one of several factors considered by school authorities.
That decision went through on the swing vote of liberal justice Sandra Day O'Conner, who was replaced last year by the conservative Samuel Alito. Chief Justice Roberts is another recent addition to the court on Bush's nomination.
"We knew that the confirmation of Chief Justice Roberts and of Justice Alito would be a setback for civil rights, but it's painful to watch years of progress undone so recklessly," said People For the American Way Foundation president Ralph Neas.
Roberts wrote that permitting "racial balancing as a compelling state interest would justify the imposition of racial proportionality throughout American society," contrary to the constitutional right to equal protection.
The court's only black justice, Clarence Thomas, a conservative opponent of affirmative action, backed the majority. "What was wrong in 1954 cannot be right today," he wrote.
But Justice Anthony Kennedy, while backing the majority, left the door open to some race-based admissions while stressing that "other demographic factors, plus special talents and needs, should also be considered."
