The U.S. Supreme Court has expressed the wisdom that California voters lacked when they passed Proposition 209, banning affirmative action in higher education.

On Monday, a majority of justices ruled that it is constitutional for colleges to consider race and ethnicity in admitting students.

The decision won't affect admission programs at California's public universities. Graduate schools and the top UC campuses continue to struggle to find ways around Proposition 209 to attract minority students.

But the ruling will uphold the efforts of private schools that receive federal money to pursue minority students, and it will send a strong signal to businesses looking for guidance in recruiting employees.

The court's 5-4 ruling is a powerful confirmation of the importance of diversity on campuses. The benefits are evident not only in the classroom, but also in the war room and the boardroom.

In briefs supporting affirmative action, corporate executives and retired generals argued that elite colleges and universities must graduate diverse leaders to run the military and help businesses compete in a global marketplace.

Justice Sandra Day O'Connor agreed, writing for the majority in a case involving the University of Michigan Law School. She cited the need for the ``effective participation by members of all racial and ethnic groups in the civic life of our nation.''

What universities cannot do, the court said in a second decision, is rely on arbitrary and mechanical methods of evaluating race or ethnicity. It rejected the University of Michigan's system of assigning substantial bonus points to Hispanics, African-Americans and Native Americans in undergraduate applications. Using race as an overriding feature is discriminatory; it fosters quotas, which the court outlawed in the 1978 case University of California Regents vs. Bakke.

However, a school can seek a ``critical mass'' of minority students to further racial understanding. And it can use race as a ``plus factor'' in individual admission decisions, O'Connor wrote, as long as it's considered along with a person's other talents, achievements and background.

These criteria are vague but appropriate. The admissions process is complex and should be subjective. Schools should consider a slew of factors in assembling a well-rounded, multi-talented and multicultural class. Race is one; SAT scores are another. Neither alone should be disproportionate.

Arbitrary point systems make it simpler to choose applicants, but they stir resentment. Schools like Stanford have achieved a diverse student body without resorting to them, by putting more effort and money into recruiting minorities and evaluating each application.

But that small upfront investment in diversity will yield a big payoff for the nation.