The U.S. Supreme Court on Tuesday further undermined the use of racial preferences in higher education by upholding a voter-approved Michigan law that banned the practice in decisions on which students to admit to state universities.

The 6-2 vote and the four opinions issued by justices in the majority revealed divisions on the court as to the legal rationale in rejecting civil rights groups' challenge to the ban. Justice Sonia Sotomayor, who wrote the sole dissenting opinion, read excerpts from the bench, calling the decision a blow to "historically marginalized groups, which rely on the federal courts to protect their constitutional rights."

The court emphasized that it was not deciding the larger and divisive question of whether affirmative action admission policies can be lawful.