A U.S. district judge has ruled that the Prince George's County school system's practice of transferring teachers from one school to another to achieve racial balance is constitutional and can be continued.

Judge Frank A. Kaufman, in a decision released by the school system yesterday, said that the policy is a valid way "to eradicate the vestiges of unconstitutional segregation in the Prince George's County public schools."

Although Kaufman ruled in favor of the board's reassignment policy, he said that the county's goal that no fewer than 30 percent of a school's faculty be composed of minorities is "unrealistic."

"Because the parameters of the present plan are not calibrated to the relevant black labor group, i.e. black teachers in the county, they result in an overly broad remedy for the discrimination the board seeks to cure," Kaufman wrote.

Kaufman and lawyers for the board will meet next week to determine what the lower number should be, said school board member Marcy Canavan.

Kaufman's ruling came in response to a Justice Department lawsuit alleging that the transfer policy discriminates against white teachers, who complained they were being transferred instead of black teachers with less seniority. The agency, which filed the lawsuit along with 12 teachers, contended that the policy was unnecessary because Kaufman ruled in 1983 that the schools were adequately integrated.

School officials interpreted the 1983 ruling to mean that while quotas were not mandated by the court, they still are necessary to maintain an integrated staff.

"We are very pleased with the decision," said Andrew Nussbaum, an attorney for the Board of Education. "When the lawsuit was filed we thought {the Justice Department} was wrong. We felt that we were acting constitutionally and within the law. Today, Judge Kaufman ruled that that was the case."

The case was seen by school officials and segregation analysts nationally as a test case. Teacher reassignment is widely used to achieve racial quotas in school systems.

Justice Department spokeswoman Amy Casner said that officials had not read the judge's decision in its entirety and were not prepared to react to it.

In 1983, Prince George's officials adopted a policy that schools have 30 percent to 50 percent minority faculty members to comply with the spirit of Kaufman's desegregation order. The reassignments were triggered when those parameters were not met.

"Most school systems thought this to be the law until the Justice Department decided to challenge it," said William L. Taylor, a civil rights lawyer and former staff director of the U.S. Civil Rights Commission.

In the spring of 1988, the school system, which has 104,000 students, transferred 13 teachers involuntarily to meet the racial guidelines. Of that number, 10 are white.

Justice Department officials sued, arguing that any kind of hiring or promotion policies based on achieving racial quotas was illegal. They said it was the first time the department had challenged a public body's policy for staff transfers and reassignments.

For this reason, the case was closely watched by education officials around the country.

The decision "will make it clear that this is an important part of school desegregation," said Taylor. "Schools ought not be identifiable by the race of faculty and that's why you need desegregation. But I don't know that this is going to work a real change around the country."