MADISON, Wis. (AP) – A judge upheld Wisconsin’s constitutional ban on same-sex marriage Friday, rejecting a challenge that claimed the 2006 referendum was improperly put to voters.

Dane County Circuit Court Judge Richard Niess dismissed a lawsuit brought by a University of Wisconsin-Oshkosh political science instructor claiming the referendum wrongly put two issues to voters at the same time.

The referendum asked voters whether to rewrite the constitution to define marriage as between one man and one woman and outlaw the state from granting a similar legal status to unmarried individuals. Nearly 60 percent of voters approved.

“Today’s ruling defeats a legal challenge that was aimed at undermining the will of Wisconsin voters,” said Attorney General J.B. Van Hollen, a Republican whose office defended the amendment.

Critics said lawmakers unfairly wrapped two questions into one amendment: whether to ban gay marriage and whether to ban civil unions. The lawsuit brought by William McConkey of Baileys Harbor, Wis., claimed the amendment violated a clause in the state constitution limiting referendum questions to a single subject.

Niess, appointed by Democratic Gov. Jim Doyle in 2004, disagreed in a ruling from the bench after hearing oral arguments on Friday.

“The two propositions ... are two sides of the same coin,” he said. “They clearly relate to the same subject matter and further the same purpose: the preservation and protection of the unique and historical status of traditional marriage.”

McConkey, a married, straight man who has a gay daughter, said he would ask his lawyers to file an appeal. If so, the Wisconsin Court of Appeals would be required to review the case.

“I’m disappointed, very disappointed,” he said. “I’m not totally surprised because it was based on a narrow interpretation of the law. But if you look at the big picture and the rights of people, I’m terribly disappointed.”

Niess noted his ruling did not address whether the amendment was good public policy or whether it violated the U.S. Constitution’s equal protection clause. He said the case only involved a “limited, and purely procedural challenge to the marriage amendment.”