The Supreme Court upheld a Michigan ban on affirmative action

The Supreme Court upheld a Michigan ban on affirmative action, a ruling that will make it easier for states to bar public universities from considering race in admissions.

The ruling leaves in place a Michigan constitutional amendment, approved by voters in 2006, that bans preferential treatment based on race, ethnicity or gender in state and local hiring practices and in admissions to public colleges. It is likely to embolden opponents of affirmative action, who plan to put similar measures on the ballots in other states.

The high court's decision is a blow to the University of Michigan in Ann Arbor, which has come under fire for low minority enrollment, MLive reports.

Justice Anthony Kennedy wrote the majority opinion, and the court was divided 6-2, with Justice Elena Kagan recusing herself from the case; she was the U.S. solicitor general when the case was before the lower courts.

Blacks comprise just 4.6 percent of undergraduates this year, compared to 8.9 percent in 1995 and 7 percent in 2006.

The ruling effectively upholds similar bans in five other states: Arizona, Nebraska, Oklahoma, California and Washington.

California passed its ban on affirmative action in 1996, and the state's public schools have since experienced low minority enrollment. In 2010, 3.4 percent students in the University of California system were black and 5.2 percent of students in the California State University system were black.