WASHINGTON » The Supreme Court is broadening its examination of affirmative action by adding a case about Michigan’s effort to ban consideration of race in college admissions.

The justices already were considering a challenge to the University of Texas program that takes account of race, among many factors, to fill remaining spots in its freshman classes. The Texas case has been argued, but not yet decided.

The court today said it would add the Michigan case, which focuses on the 6-year-old voter-approved prohibition on affirmative action and the appeals court ruling that overturned the ban. The new case will be argued in the fall. A decision in the Texas case is expected by late June.

The dispute over affirmative action in Michigan has its roots in the 2003 Supreme Court decision that upheld the use of race as a factor in university admissions. That case concerned the University of Michigan law school.

In response to the court’s 5-4 decision in that case, affirmative action opponents worked to put a ballot measure in front of voters to amend the state constitution to outlaw preferential treatment on the basis of race and other factors in education, as well as government hiring and contracting. In November 2006, 58 percent of Michigan voters approved the measure.

Civil rights groups sued to block the provision the day after the vote. In November, the 6th U.S. Circuit Court of Appeals voted 8-7 to invalidate the ban as it applies to college admissions. It did not address hiring or contracting.

The appeals court said the constitutional amendment is illegal under Supreme Court rulings from the late 1960s and early 1980s that prohibit placing special burdens on minority groups that want to bring about changes in laws and policies. The court said that forcing opponents of the ban to mount their own long, expensive campaign through the ballot box to protect affirmative action amounts to different, and unequal, treatment.

That burden “undermines the Equal Protection Clause’s guarantee that all citizens ought to have equal access to the tools of political change,” the court said. By way of example, the court said that children of university alumni remain free to lobby lawmakers and university officials to adopt policies to take family ties into account in admissions.

The 6th Circuit divided along ideological lines, with its more liberal judges in the majority.

Michigan Attorney General Bill Schuette asked the Supreme Court to review the 6th Circuit’s ruling. “Entrance to our great colleges and universities must be based upon merit, and I remain optimistic moving forward in our fight for equality, fairness and rule of law at our nation’s highest court,” Schuette said today.

In the Texas case, a white student who was denied admission to the University of Texas is suing to overturn the school’s use of race among many factors to fill out its incoming freshman classes. The bulk of the slots go to Texans who graduated in the top 10 percent of their high school classes.

The Michigan case is Schuette v. Coalition to Defend Affirmative Action, 12-682.