Pro-affirmative action demonstrators bearing "Fight For Equality" placards descended on the Supreme Court Monday as justices prepared to hear fresh arguments in cases testing when race may be used as a basis for assigning students to public schools.

Parents in Louisville, Ky., and Seattle are challenging school assignment plans that factor in a student's race in an effort to have individual school populations approximate the racial makeup of the entire system. Federal appeals courts have upheld both programs.

On the sidewalk in front of the Supreme Court, several hundred of pro-affirmative action demonstrators marched in a brisk wind to dramatize their issue. A parent-teachers group from Chicago and several civil rights groups were among those sponsoring the demonstration.

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Demonstrators chanted "Equal education, not segregation" and "We won't go to the back of the bus, integration is a must." Some held signs that read "Stop racism now." Among the crowd were representatives of the National Organization for Women, the NAACP and students from Howard University.

"It's ridiculous to separate us. We worked hard to get everyone together. Why separate us now?" said Jade Johnson, 15, of Washington D.C., who attends Theodore Roosevelt Senior High School in the district. Johnson said she came to the demonstration instead of going to school.

Though outnumbered, there were some in the crowd from the other side.

"Regardless of how well-motivated, allowing the state to engineer racial mixing only creates racial stereotypes and increases racial tension," said Terry Pell, president of the Center for Individual Rights, a public interest law firm. "The court needs to put an end to state-mandated tinkering with race."

The school policies in contention are designed to keep schools from segregating along the same lines as neighborhoods. In Seattle, only high school students are affected. Louisville's plan applies systemwide.

"The plan has prevented the resegregation that inevitably would result from the community's segregated housing patterns and that most likely would produce many schools that might be perceived as 'failing,"' the Seattle school district said in its brief to the high court.

The Bush administration has taken the side of the parents who are suing the school districts, much as it intervened on behalf of college and graduate students who challenged affirmative action policies before the Supreme Court in 2003.

In 2003, the court upheld race-conscious admissions in higher education in a 5-4 opinion by Justice Sandra Day O'Connor.

O'Connor, however, has since retired and been replaced by conservative Justice Samuel Alito. Lawyers on both sides of the issue presume that Alito is inclined to oppose the school plans.

About 400 of the nation's 15,000 school districts are under court orders to desegregate. It is believed that hundreds more voluntarily take race into account.

There are no firm figures, although the Pacific Legal Foundation of Sacramento, Calif., said up to 1,000 districts voluntarily use race as a factor in school assignments, drawing boundaries, deciding where to locate new buildings and in other ways. The foundation opposes race-based policies.

Seattle has tried for years to achieve racial diversity in its schools in the face of persistent segregated housing patterns. The city's schools have never been subject to court order. Seattle put the assignment system at issue in place in 1998, but suspended it after parents sued.

Click here to read the Seattle case arguments (pdf)

The Louisville schools, with a history of state-imposed segregation, were under federal court supervision for 25 years. The Jefferson County Board of Education, which encompasses Louisville,came up with its own plan to maintain integrated schools shortly thereafter.

Click here to read the Jefferson County case arguments (pI)

But the policy denigrates children's self-worth by color-coding them throughout their school years, said the legal brief for Crystal Meredith, the Louisville parent who sued after her son was denied his first choice of which school to attend.

The cases are Parents Involved in Community Schools v. Seattle School District No. 1, 05-908; and Meredith v. Jefferson County Board of Education, 05-915.