Is the University of Michigan making the best case for affirmative action?

Some of its own supporters doubt it. As the six-year battle over Michigan's admissions policy nears a U.S. Supreme Court verdict likely to have far-reaching consequences, those who back race preferences are increasingly dissatisfied with the university's defense.

Its argument is based on the notion that a diverse enrollment forges more thoughtful, tolerant and civic-minded students. Some liberal backers fear Michigan could lose the coming decision -- the first Supreme Court pronouncement on race preference in college admissions in a quarter-century and which will apply to both private and public universities -- because, they say, the diversity rationale suffers from flawed analysis and weak social-science research. They prefer the traditional justification: that affirmative action is needed to redress the effects of past racial discrimination.

And yet in recent decades, the court has steadily whittled away at the notion that race preference is needed to remedy the effects of discrimination. The court has held that the argument is only valid if the same institution giving preference to minorities recently discriminated against them.

"Diversity is a Johnny-come-lately afterthought," says Colin Diver, president of Reed College in Portland, Ore., and former dean of the University of Pennsylvania Law School. "The strongest argument for affirmative action is societal debt -- evening the playing field." But through past decisions, "the Supreme Court has taken that argument away from us. The court has really painted us into a box," he adds.

Even minority students find fault with the diversity argument. Erika Dowdell, an African-American student and affirmative action activist who graduated from Michigan last year, says the diversity rationale "is not a good move for students of color. ...The term 'diversity' gets tossed around so much that it's offensive to students of color. It sounds as if we're just in college to enrich the education of white students."

The diversity legal argument first gained prominence in the court's 1978 Bakke decision. In that case, the court rejected racial quotas and ordered the admission of Allan Bakke -- a white applicant who claimed he had been a discrimination victim -- to medical school at the University of California at Davis. But the decision also upheld race preference as an allowable factor in admissions decisions on a 5-4 vote.

Four liberal justices justified affirmative action on the grounds that it redresses past racial discrimination. But Justice Lewis Powell Jr., author of the decisive tie-breaking opinion, cited diversity's benefits instead. A diverse student body, he wrote, promotes "the atmosphere of speculation, experiment and creation so essential to the quality of higher education."

The Powell decision marked the beginning of a quarter of a century in which the values of diversity were extolled and promoted far and wide in American society, including the workplace, the military and popular culture. But however desirable diversity may be as a cultural or economic principle, its legal foundation is another matter. And at law, the diversity rationale is in grave danger in the Michigan cases where rejected white candidates sued the university, arguing they were passed over for less-qualified minority candidates.

Michigan's undergraduate policy gives a 20-point boost to minority applicants on a 150-point admissions scale, while its law school considers race among other factors. Marvin Krislov, Michigan general counsel, says the university "focuses on diversity because that really is part of our educational mission. It's also within the legal framework laid down by Bakke."

Though still widely regarded as the law of the land, the diversity rationale has its drawbacks. Critics ask, for instance, how racial diversity enriches classroom discussion in such fields as physics, tax law, and ancient Greek. And if a diverse student body contributes to a "robust exchange of ideas," as Justice Powell argued, why do universities give preference only to blacks, Hispanics and Native Americans?

"The commitment to diversity is not real," says Samuel Issacharoff, a Columbia University law professor who represented the University of Texas Law School in the 1996 Hopwood case, in which the U.S. Court of Appeals for the Fifth Circuit struck down a minority race preference there. "None of these universities has an affirmative-action program for Christian fundamentalists, Muslims, orthodox Jews, or any other group that has a distinct viewpoint. How many schools reach out for neo-Nazis?"

The social-science evidence on diversity is also much debated. Patricia Gurin, a Michigan social psychologist helping the school in the lawsuit, analyzed Michigan and national data and concluded that students in diverse environments "learn better" and think "in deeper, more complex ways," although there's no evidence that such enlightenment translates into higher grades or test scores.

Ms. Gurin's findings have come under fire from the conservative National Association of Scholars who say they are based on student responses to questionnaires, which can be unreliable. She also acknowledges that even if a university practices race preference, students may not benefit unless the school promotes interracial contact through multicultural events, ethnic studies courses and the like. Just having a high proportion of minorities in the student body isn't enough.

In another study, former Ivy League presidents William Bowen and Derek Bok found that black students given preference by top colleges had somewhat lower grades and graduation rates than white students, but nonetheless often attained advanced degrees and high salaries after college -- and fared better than if they had attended lower-quality schools. Critics of their work say rejected white applicants with stronger academic records would also have benefited from the enhanced opportunities.

Alexander Astin, director of the Higher Education Research Institute at UCLA, which tracks students for nine years after they enter college, says that "diversity experiences" -- interaction with other races -- have no effect on academic achievement. But, he says, all students who have more contact with other races are slightly more likely to stay in school, and are considerably more likely to apply to graduate school.

Some affirmative action supporters hope that the justices will pluck another justification -- national security and prosperity -- from friend-of-the-court briefs submitted by former military leaders and Fortune 500 businesses.

Taken together, these briefs argue that the well-being of military and corporate America depends on racially diverse leadership made possible by race preferences in college admissions. Just as an integrated officer corps sustains morale and racial harmony in the armed forces, so a diverse corporate management fosters global business relationships. Both groups contend that affirmative action is deeply ingrained in American society -- and that reverting to the policies of an earlier era would have devastating effects.

Ms. Gurin, for one, believes this defense of affirmative action is stronger than Justice Powell's. "The military and the corporations take the diversity argument a step further. It's a very complex world, and our leaders have to understand that."