The Supreme Court on Tuesday upheld Michigan's ban on using race as a factor in college admissions.

The justices said in a 6-2 ruling that Michigan voters had the right to change their state constitution to prohibit public colleges and universities from taking race into account in admission decisions. The justices said that a lower federal court was wrong to set aside the change as discriminatory.

The high court made clear that in ruling on Schuette v. Coalition to Defend Affirmative Action, it was not deciding the larger question of whether affirmative action admission policies are lawful.

"This case is not about how the debate about racial preferences should be resolved," wrote Justice Anthony M. Kennedy for the majority opinion. "It is about who may resolve it."

The justices rejected the argument made by civil rights groups that Michigan's constitutional amendment — Proposal 2, approved by voters in 2006 — barring college admissions decisions based on race imposed burdens on racial minorities in violation of the U.S. Constitution's equal protection guarantee.

Kennedy, joined by Chief Justice John Roberts and Justice Samuel Alito, said that an appeals court that threw out the law did not have the authority to do so.

The dissenting votes came from two liberal members of the court, Justices Sonia Sotomayor and Ruth Bader Ginsburg.

Sotomayor wrote that the decision was a blow to "historically marginalized groups, which rely on the federal courts to protect their constitutional rights." The court undermined its own precedents, which state that the majority cannot suppress minorities' right to participate in the political process, she added.

Justice Antonin Scalia wrote a separate opinion, joined by Justice Clarence Thomas, in which he said that challenges to laws that rest on equal protection claims must show that the law reflects a discriminatory purpose. The Michigan law did not, he said.

Justice Stephen Breyer was the only member of the liberal wing of the court to join the majority. He wrote that the ban was constitutional because the prohibition gave voters, rather the university officials, the right to decide whether to adopt race-conscious admissions policies.

Justice Elena Kagan, who had worked on the case when she was solicitor general, recused herself.

Leticia Smith-Evans, interim director of Education Group at the NAACP Legal Defense and Educational Fund, said Tuesday's decision wasn't a death-knell for admissions policies that consider race.

"While this decision is a setback for diversity efforts in Michigan, it is important to note that this case did not address the merits of race-conscious admissions, which have been previously upheld by the court, as the justices emphasized in today's ruling," Smith-Evans said.

Still the ruling was a let down for those who had hoped to see it dismantled.

Kevin Gaines, an African-American studies professor at the University of Michigan and one of the plaintiffs arguing for the removal of the ban, expressed disappointment at the decision, according to a statement released by the American Civil Liberties Union.

"Proposal 2 has meant less diversity in our universities, which has had a chilling effect on the quality of discourse in the classroom. Unfortunately, that will continue, at least for the time being, in Michigan," Gaines said.

Since the ban passed, the share of freshmen at the University of Michigan who identify as black has fallen 30 percent, prompting the Black Student Union in November to launch a social media campaign that trended nationally and spread to dozens of other major schools to highlight racial injustice on U.S. college campuses.

The effort, known by #BBUM — Being Black at U.M. — was so successful that members of the student union have met weekly with administration officials since releasing a list of demands in January to discuss ways of addressing both the plummeting enrollment figures and a range of challenges facing black students there.

Mark Rosenbaum, a lawyer for the ACLU who argued against the ban in the case, also criticized the decision.

"This case is ultimately about whether students of color in Michigan are allowed to compete on the same playing field as all other students. Today the Supreme Court said they are not," Rosenbaum said in a press release.

In an interview with Al Jazeera, Rosenbaum said that the Supreme Court's decision allows for preferential treatment on the basis of whether a student's parents attended a school or donated money, allowing the consideration of good fortune and privilege, but lets admissions officers ignore race as a factor.

"One of the things that the majority opinion does is to treat racial identity as if it was a thing of the past or as if it were invisible, and I think that's both unfair and untrue."

The case was argued in October 2013, just four months after the justices issued a narrow ruling on affirmative action in a different case involving the University of Texas at Austin.

In a lopsided 7-1 ruling in the Texas case that few had expected, the court warned that university policies that took race into account could be more vulnerable to legal challenges in the future. But the court did not strike the policy down and instead sent the case back to a lower court for reconsideration.

The Michigan case raised a different legal question, focusing not on the state's ban on affirmative action itself but on the political process that led to the policy change

Wilson Dizard contributed reporting, with wire services.