TULSA, Okla. (AP) – Supporters of Oklahoma’s recently approved ban on affirmative action in state government say they are confident the voter-approved law would survive a legal challenge.

But federal court precedent is conflicting. And if Oklahoma’s law change makes it to court, that could further raise the possibility that the U.S. Supreme Court would eventually get involved in the issue.

Oklahoma voters last week approved State Question 759, a Republican-backed plan that bans preferential treatment in state contracts or education programs based on race, gender, ethnicity or national origin. It doesn’t apply to current court-ordered programs or federally funded programs.

This week, the 6th U.S. Circuit Court of Appeals ruled against a similar voter-approved law in Michigan that bans the use of affirmative action in college admission.

The Cincinnati-based court decided the 2006 constitutional amendment was illegal, in part because it presented an extraordinary burden to opponents who would have to mount a long, expensive campaign through the ballot box to protect affirmative action.

But a similar voter-approved ban in California had already upheld by the 9th U.S. Circuit Court of Appeals in San Francisco. Supporters of Oklahoma’s law point to that case, noting that the state’s ballot measure was modeled after California’s plan, as well as other approved proposals in Nebraska, Washington and Arizona.

However, both of those decisions are geographically limited. The decision in the Michigan case applies to states within in the 6th Circuit, which also include Kentucky, Ohio and Tennessee. The same goes for the western states covered by the 9th Circuit.

Oklahoma falls under the 10th Circuit, so if Oklahoma’s law gets challenged and makes its way to the federal appeals court, it would raise the odds that the U.S. Supreme Court could get involved to set a national standard.

Republican Rep. Mike Jackson, who helped write Oklahoma’s new law, isn’t worried about a challenge either way. He said it would stand up to legal scrutiny.

“I feel confident State Question 759 will pass constitutional muster and go a long way in making sure hiring practices are equal for everyone,” Jackson said Friday.

“Affirmative action has probably over-served its purpose,” added Rep. Mike Ritze, a Republican co-writer. “We’ll see what happens, but the state could also step up and nullify whatever the government tries to do against them. The state could still ignore it.”

Opponents said it was too soon to tell whether the ruling in the Michigan case could impact Oklahoma’s law or the U.S. Supreme Court’s decision to take up one of the laws.

Still, Ryan Kiesel, executive director of the American Civil Liberties Union’s Oklahoma chapter, was encouraged, based on reports he read on Thursday’s decision in Michigan.

“Any decision there may not necessarily be binding in Oklahoma, so it’s too early to say it’s going to have an impact here in Oklahoma, but it’s encouraging,” he said.

The Supreme Court heard arguments last month in the case involving white Texas student Abigail Fisher, who contends she was discriminated against when the University of Texas did not offer her a spot in 2008 because of its program that considers race in college admissions. A ruling is expected this summer.