At the same time, the practical effect could be limited.
David Bositis of the Joint Center on Political and Economic Studies, a black think tank, said the rulings will probably make many schools readjust their minority-advancement programs so they pass constitutional muster.
"Most that want to have affirmative action programs will continue to have them," he predicted. He said the decisions seem so narrowly tailored to the facts in front of the court that they may have little meaning off campus or in other aspects of American life.
The two rulings Monday were the court's first statement on racial preferences in 25 years.
In a 5-4 decision, the high court found the University of Michigan's law school admission policies were legal and key to creating a diverse student body.
But in a companion case, the court restated its opposition to racial quotas, ruling Michigan went too far in its undergraduate admissions policy.
By a 6-3 margin, the court struck down a "point system" which automatically awarded 20 points to minorities – one-fifth of the total needed for admission and far more than the points awarded for SAT scores or writing skills.
The split decision reflects the national mood. Ambivalence over affirmative action has been as deep-seated as the wish to correct age-old imbalances among the races and between the sexes.
Ask Americans if they support efforts to advance minorities, and most will say yes.
Ask them if they support doing everything possible even if it means giving minorities preferential treatment, and they are much less sure. Ask whether employers or schools should use racial quotas to guarantee diversity, and they say no.
In short, Americans appear to favor a focus on minority advancement as long as the tools of achieving that are not too explicit or rigid — whether in the classroom, the boardroom, the housing development or the battlefield.
The debate could now move from the court to the process of selecting new members of it.
Conservatives angered by the ruling will probably react by pressing harder for any new justices named to the high court to be strong affirmative action opponents, reports The New York Times.
Affirmative action opponents are said to be upset that David Souter, an appointee of the first President Bush, and Sandra Day O'Connor, whom President Reagan named to the court, supported the principle of racial preferences.
Conservatives hope to avoid similar surprises next time. While no justice has announced a retirement, the affirmative action decisions were already changing the odds on possible replacements for any justices who do opt to step down.
For example, conservatives may now reject White House counsel Alberto Gonzalez, who is believed to be sympathetic to the case for racial preferences, and may have helped shape the White House brief on the case to oppose types of preferences but not the concept overall.
Even some who support affirmative action were unhappy with the decisions, and said the rulings were, at best, a do-no-harm event that leaves the status quo largely in place. As the NAACP put it, the court endorsed a "modest consideration of race" in university education.
Even so, the decisions were the most significant on the subject since 1978, when the court set the pattern of ambiguity by outlawing racial quotas in education but allowing race to be considered.
Former University of Michigan president Lee Bollinger hailed the rulings in an interview on the CBS News Early Show.
"What yesterday's decision did was make clear majority of the court which held an eloquently stated reason that race can be considered to get an innovative student body in order to better educate all students for the modern world," he said. "It's profoundly important and now gives a clear Supreme Court precedent on this major issue."
Many of the inequities that drove policy-makers to introduce racial preferences persist, despite marked progress. More than one-quarter of whites, but less than 17 percent of blacks and 11 percent of Hispanics, graduate from college.
In the work force, the percentage of blacks who work as managers in professional fields has crept up to a little over 8 percent from 5.6 percent in two decades. Five percent of Hispanics hold those jobs, up from 2.6 percent.
In the armed forces, blacks — 13 percent of the population — make up 20 percent of the personnel but less than 4 percent of special forces, and they are underrepresented in the senior officers' ranks of every service.
With corporate America under pressure to employ a diverse work force and sell to a multicultural marketplace, dozens of Fortune 500 companies supported the University of Michigan in the case.
"It makes all the business sense in the world," Edd Snyder, spokesman for General Motors, said earlier in siding with the university. "We sell vehicles in every corner of the globe" and need workers who reflect those customers.
"Where do you get that employee base? From universities and colleges."