DID MICHIGAN VOTERS violate the U.S. Constitution, when they amended their state constitution to prohibit public universities from taking race, sex, color, ethnicity, or national origin into account when making hiring, contracting or admissions decisions?

That is the question the U.S. Supreme Court confronted on Tuesday, when it returned to the controversial problem of affirmative action only a few months after its last ruling on the issue.

Although some were surprised that the court returned to affirmative action so soon, the case argued on Tuesday asks a very different question from the one the court answered last June. Then, the question was: Are state universities allowed to use race-based affirmative action? On Tuesday, the question was: Who decides when to end it?

The court would have had to answer this question soon, because lower courts have reached conflicting conclusions. When the people of California passed Proposition 209, which ended the use of affirmative action at that state’s public universities, the Ninth Circuit Court of Appeals agreed that the people of the state had the right to decide by referendum that it was time to end the use of race in college admissions.

When the people of Michigan passed a parallel measure, called Proposal 2, however, the Sixth Circuit Court of Appeals objected. One of the most fundamental responsibilities of the Supreme Court is to make sure that the laws are enforced uniformly across the country. So when a “circuit split” of this sort arises, the Court rarely waits long to intervene.

To the Ninth Circuit judges, Proposition 209 presented an easy case. The 14th Amendment to the U.S. Constitution forbids any state from denying to “any person within its jurisdiction the equal protection of the laws.”

Although the Supreme Court repeatedly has held that public institutions may use race-based forms of affirmative action, in the hope of thereby eventually producing a more equal society, such affirmative action programs are not constitutionally required.

The Supreme Court also has repeatedly held that “a core purpose of the 14th Amendment was to do away with all governmentally imposed discrimination on race.” In the view of the Ninth Circuit judges, that is exactly what Proposition 209 does: It requires the treatment of all persons equally, without regard to race, sex, color, ethnicity or national orign. Hence, they approved it.

The Sixth Circuit judges, however, looked at the matter very differently, focusing not so much on the substance of the measure as on the political process that led to its adoption.

They note that Michigan has an ordinary political process for setting educational policy at the state colleges and universities. Each of these has an elected Board of Regents, with authority over the educational programs at their respective schools. On the advice of the college administrators, who strongly favor the use of affirmative action, these boards want such policies to be continued.

What the people of Michigan have done, by enacting Proposal 2, was to use an extraordinary political process — the adoption of a constitutional amendment — to take the decision about affirmative action out of the ordinary political process. In the eyes of the Sixth Circuit judges, a majority of voters in the state of Michigan now have made it harder for minority voters in Michigan, who, as a group, overwhelmingly favor affirmative action, to get their preferred policy enacted into law.

They argued that the adoption of Proposal 2 was analagous to what the people of Seattle did, in 1978, when they secured the adoption of a state initiative that barred local school boards from busing students to distant schools to achieve racial integration.

Just as the Supreme Court ruled that the Washington initiative violated the constitutional guarantee of equal protection by making it harder for minority voters to win the adoption of policies they favor, the Sixth Circuit judges concluded that so, too, does Proposal 2.

The judges of the Ninth Circuit have the better argument. They argue that “even a state law that does restructure the political process can only deny equal protection if it burdens an individual’s right to equal treatment.” The “political process” argument of the Sixth Circuit, however, depends on the theory that the Equal Protection Clause protects the rights of minorities as groups, who are assumed to have common collective interests, in the adoption of racially preferential policies.

The Constitution, however, says that it protects every “person” from discrimination, which is exactly what the voters of Michigan have attempted to do.

Joseph R. Reisert is associate professor of American constitutional law and chairman of the department of government at Colby College in Waterville.