The U.S. 6th Circuit Court of Appeals ruled en banc Thursday that Michigan’s voter-approved ban on affirmative action was unconstitutional.

The court issued an 8-7 decision to overturn a state ballot initiative — commonly known as Proposal 2, which was voted into law in 2006 — that banned the use of “preferential treatment” in state decisions regarding university admissions or employment on the basis of race, sex, color, ethnicity or national origin.

The ruling was made by all 15 judges on the 6th Circuit Court of Appeals, at the request of Michigan Attorney General Bill Schuette, a defendant in the case. A three-judge panel of the 6th Circuit Court of Appeals made an initial ruling against Proposal 2 in July 2011.

The majority ruled that the ban on the basis of race is a violation of the Equal Protection Clause of the 14th Amendment to the U.S. Constitution and therefore unconstitutional. The decision overturns a previous decision made by the U.S. District Court for the Eastern District of Michigan at Detroit, which ruled Proposal 2 to be constitutional.

The majority opinion was based on two primary arguments, rested on the argument that admissions decisions can be considered a part of the political process. Judge R. Guy Cole Jr. wrote for the majority, arguing that Proposal 2 is unconstitutional based on the fact that it primarily harms minorities by reordering the political process and placing undue burden on them.

“Because less onerous avenues to effect political change remain open to those advocating consideration of non-racial factors in admissions decisions, Michigan cannot force those advocating for consideration of racial factors to traverse a more arduous road without violating the Fourteenth Amendment,” Cole wrote. “We thus conclude that Proposal 2 reorders the political process in Michigan to place special burdens on minority interests.”

Law Prof. Mark Rosenbaum, who helped argue the case on behalf of the plaintiffs, said he was overwhelmed by the decision and excited about its implications.

“It’s a landmark civil rights issue,” Rosenbaum said. “It is not about the constitutionality of affirmative action; it is a bigger story than that. It’s about access to the political process. It is about whether or not a popular initiative can cut minorities — people of color — out of the political process.”

Rosenbaum said even if the defendants, including Schuette, appeal the decision, the ruling will take immediate effect, meaning the University could choose to use race as a factor in admissions decisions.

In a statement, Schuette said he intends to appeal the decision to the U.S. Supreme Court on the basis that the Michigan Civil Rights Initiative — the amended section of the constitution that effectively banned affirmative action — is not only constitutional, but also approved by a majority of Michigan voters.

“MCRI embodies the fundamental premise of what America is all about: equal opportunity under the law,” Schuette said. “Entrance to our great universities must be based upon merit. We are prepared to take the fight for quality, fairness and the rule of law to the U.S. Supreme Court.”

In order to have the case heard at the Supreme Court level, Schuette must file a petition of certiorari within 90 days of Thursday’s decision.

In his dissenting opinion, Judge Danny Boggs drew on the fact that Proposal 2 was enacted by voters to make his case.

“We have the citizens of the entire state establishing a principle that would, in general, have seemed laudable,” Boggs wrote.

Boggs also wrote in the dissent that the majority’s case was a stretch and relied on tenuous precedent. He responded to the majority’s assertion that admissions decisions fall within the jurisdiction of political processes, contending that such an argument does not have historical backing and that Proposal 2 is inherently not discriminatory.

“Under these circumstances, holding it to be a violation of equal protection for the ultimate political authority to declare a uniform policy of non-discrimination is vastly far afield from the Supreme Court precedents,” Boggs wrote.

In a statement, University spokesman Rick Fitzgerald said the University is reviewing the decision, but because there are multiple lengthy opinions, it could take some time to fully understand the ruling's implications.

George Washington, an attorney for By Any Means Necessary — a pro-affirmative action group that helped argue the case before the court — said he would like to see a turnaround from the drop in minority enrollment as a result of the decision.

“It is a tremendous victory for black and Latino students and for the movement that fought for affirmative action for many years,” Washington said. “It means that thousands of black, Latino and Native American students who would not have the chance to go to our most selective colleges will now have that chance.”

Residential College Prof. Carl Cohen, a leading proponent of Michigan’s Proposal 2, said the majority opinion is incorrect in its assertion that Proposal 2 violates the Equal Protection Clause because it places an undue burden on those who seek preference, adding that the opinion is based on ludicrous, circuitous logic.

“The argument upon which the 6th Circuit Court of Appeals based its reversal is absolutely unbelievable,” Cohen said. “That's really acrobatic, that the constitutional amendment that says you may not give preferences violates the constitutional amendment that says you may not give preference.”

Daily News Editor Andrew Schulman and Daily Staff Reporter Peter Shahin contributed to this report.