Michigan Affirmative Action banBy a 6-2 vote, the U.S. Supreme Court on Tuesday upheld a voter-approved Michigan law that banned the use of racial preferences to admit students to state universities.

The court emphasized that it wasn’t deciding the larger and more divisive question of whether affirmative action policies can be lawful. However, the decision made it clear that voter-approved bans on this practice can withstand legal challenges. It could encourage other states to pass similar bans, and deter challenges to existing bans in seven other states.

Civil rights groups have argued that the 2006 Michigan constitutional amendment – passed as a ballot initiative – imposed burdens on racial minorities which violated the U.S. Constitution’s guarantee of equal protection.

In November 2012, a divided 6th U.S. Circuit Court of Appeals in Cincinnati ruled Michigan’s ban unconstitutional. This prompted the state to appeal this decision to the Supreme Court.

Michigan’s Republican Attorney General, Bill Schuette, said in an interview that the Supreme Court provided other states a “constitutional road map” if they wish to enact similar laws. He added the Justices with their decision had “heard the voices of voters who overwhelmingly voted to require equal treatment in admissions.”

Not surprisingly, the ruling was criticized by civil rights activists and Democrats. Justice Sonia Sotomayor wrote the sole dissenting opinion and read excerpts from the bench. She called the decision a blow to “historically marginalized groups, which rely on the federal courts to protect their constitutional rights.”

The opinions issued by four justices in the majority revealed differences in the legal rationale to reject civil rights’ groups challenges to the ban. Justice Anthony Kennedy wrote an opinion and was joined by Chief Justice John Roberts and Justice Samuel Alito, which said that the lower court which struck down the ban lacked the authority to do so.

“This case is not about how the debate about racial preferences should be resolved,” Kennedy wrote. “It is about who should resolve it.”

Justice Antonin Scalia wrote another opinion and was joined by Justice Clarence Thomas. He wrote that challenges to laws that rest on equal protection claims must show that the law reflects a discriminatory purpose, and the voter-approved Michigan law did not.