LANSING, Mich. (AP) – Michigan is one of 11 states where voters will decide ballot proposals related to same-sex marriage on Nov. 2.

But the debate in Michigan is broader than in many other states. Because of the way Proposal 2 is worded on the Michigan ballot, opponents say they are worried about its possible effect on domestic partner benefits for both same-sex and opposite-sex unmarried couples.

Others argue Proposal 2 would have little or no effect on health insurance and other benefits offered to some unmarried couples, and say opponents are trying to divert attention from the core issue of defining marriage.

Courts likely would decide the domestic benefits issue if voters approve Proposal 2, which seeks to define marriage as a union between one man and one woman in the state constitution.

“If it passes, it is a virtual certainty that there will be court challenges,” said Jeff Horner, a research associate with the nonpartisan Citizens Research Council of Michigan, based in Livonia. “And it will come down to a judge’s interpretation.”

That interpretation could vary widely depending on the judge and the basis of the lawsuit, Horner and others say.

Marriage already is defined as a union between one man and one woman in Michigan law. Supporters say they want the language put in the state constitution to protect it from judges and politicians who might want to change the law.

Some argue Proposal 2 goes farther than the current statute because it includes language that the one-man, one-woman marriage “be the only agreement recognized as a marriage or similar union for any purpose.”

Opponents say that would ban civil unions and take away the health insurance and prescription drug coverage offered by some employers to unmarried couples.

Marlene Elwell, campaign manager for the pro-Proposal 2 group Citizens for the Protection of Marriage has said opponents are distorting her group’s objectives. She said the amendment wouldn’t affect private employers and may not affect public ones, either, depending on what court challenges are brought if the amendment passes.

Some public employers say they doubt Proposal 2 would affect their benefits packages.

University of Michigan President Mary Sue Coleman sent an email to faculty and staff, saying the school does not believe Proposal 2 would be relevant to decisions about the benefits offered to employees and their dependents. But Coleman acknowledged the possibility of a legal challenge if Proposal 2 passes.

“The University of Michigan offers benefits programs to help recruit and retain the best and brightest employees,” Coleman wrote. “If we are challenged, we will vigorously defend our right to offer such benefits.”

Private employer DTE Energy Co. based its domestic partner benefits package on federal law, according to spokesperson Scott Simons.

“We do not anticipate it [Proposal 2] would have any impact,” Simons said.

Gary Glenn, a Proposal 2 supporter and president of the American Family Association of Michigan, said such statements undercut the opposition’s critique.

“They clearly refute the charges made by opponents of Proposal 2,” he said. “End of story.”

But many Proposal 2 opponents interpret the proposal differently.

The Michigan State AFL-CIO is urging members in its affiliated unions to vote against the proposal, saying it eventually could take away benefits that have been negotiated into contracts covering opposite-sex and same-sex couples and their children.

“Public employees have seen a steady erosion of bargaining rights, items that can no longer be on the bargaining table, and this proposal adds to the list,” an AFL-CIO statement said.

Dana Houle, a spokesperson for an anti-Proposal 2 group called Coalition for a Fair Michigan, said labor and civil liberties lawyers say the proposal would undermine domestic partner benefits offered by public employers.

The banning of civil unions would make it more difficult for private employers to document relationships when determining who should be eligible for benefits, Houle added.

“Even for those employers not directly affected, it would make it more difficult to administer the program,” he said.

Many observers say the way the constitutional amendment is applied depends on how the proposal, if passed, would be challenged in court.

“The real issue is will someone challenge it, and on what basis will they challenge it,” said John Pirich, an attorney with Honigman Miller Schwartz and Cohn in Lansing and a faculty member at the Michigan State University College of Law. “Its really nebulous. It’s hard to say how it will impact anything.”