Nearly 25 years ago, a narrowly divided Supreme Court held in the Bakke case that while fixed racial quotas were unconstitutional, race could be a "plus factor" for minority applicants. The tortured logic of this distinction was justified, the court held, by universities' compelling interest in racial diversity. Since then, conservatives have successfully challenged affirmative-action programs in the university systems of several states, notably California and Texas. Another Supreme Court confrontation drew closer last week, when the justices agreed to decide whether the admissions practices at the University of Michigan illegally discriminate against white applicants. The issue should get a thorough airing: on the record will be hundreds of pages of studies on the academic benefits of racial diversity compiled by a Michigan professor. Curt Levey of the Center for Individual Rights, which brought the suit, is hoping for a definitive ruling that could affect not just public universities but every college that accepts federal money, even by way of student loans. Theodore Shaw of the NAACP Legal Defense Fund, which supports affirmative action, gamely asserts that among several similar suits making their way through the courts, this is one of the stronger cases from the defense side. But Shaw, well aware that Bakke was decided by only one vote, by a court that has only grown more conservative since, adds that "if we had our druthers we wouldn't be here at all."