Despite all the drama, the final decision–due by early summer–may be more likely to tinker with the law than to upend it. In the 1978 Bakke case, a fractured court ruled that quotas and two-track admissions systems were unconstitutional, but upheld the vague notion of using race as one of many “plus” factors in admissions. The Michigan plaintiffs hoped for a new decision that would bar all use of race. And nearly everyone hoped the court would clarify the murky standard set by Bakke. But last week’s arguments revealed another divided court with Sandra Day O’Connor as the swing vote. Court watchers think Michigan’s programs could be vulnerable, but they doubt the splintered court will ban racial preferences altogether.

Opponents of affirmative action thought they’d found a solid test case in Michigan. Its undergrad program uses a point system to sort through 24,000 applications a year. African-Americans, Hispanics and Native Americans get 20 extra points out of a possible 150–as do athletes and the economically disadvantaged. The law school doesn’t use points, but aims for a “critical mass” of minority students.

The plaintiffs claim both programs are thinly disguised quotas, and some of the justices clearly agreed. “Once you use the term ‘critical mass’,” said Antonin Scalia, “you’re into quota land.” Scalia also suggested that if diversity was so important, Michigan should lower its standards so more minorities could make the cut–a point echoed by Clarence Thomas, who rarely speaks from the bench. Others, including Stephen Breyer, cited the benefits of diversity to all students. And Ruth Bader Ginsburg asked about a brief by former military officers who stressed a national-security need for affirmative action in military academies.

Yet if most of the justices were searching for a legal “bright line” to decide the case, O’Connor seemed to be scouring the shadows. She appeared early on to reject the notion of banning race, but later expressed concern that preferences would continue indefinitely. O’Connor has a reputation for careful, narrow rulings, and is often reluctant to disturb decisions that the public views as settled law. “It would be shocking for her to accept an absolutist decision,” says Cardozo law professor Marci Hamilton, a former O’Connor clerk.

Though Michigan is a public university, the rulings could affect private colleges and military academies, too. Even if the court doesn’t ban racial preferences, other schools might adopt alternative policies to avoid litigation. State schools could try “percentage plans” like those in Texas, California and Florida that admit top students from all high schools. Others could increase recruiting at urban schools, or give preference to poor students. “All of that will start being documented in students’ files in a very individual way,” predicts Douglas Kmiec, dean of Catholic University Law School. And that could be exactly the kind of compromise the court has in mind.