MADISON, Wis. -- On the ballot Tuesday, the marriage amendment referendum will ask voters if they want to amend the Constitution to define marriage as between one man and one woman.

With the election nearing, WISC-TV took a look at the second sentence of the referendum question and the phrase "substantially similar."

Behind every marriage, there are pages and pages of Wisconsin statues. Those laws lay out the specifics -- who can marry, why marriage is important and how to get a license.

But none of these statutes are in the Constitution, meaning they can be changed and are open to interpretation by a court.

Some said the marriage amendment's two sentences are anything but specific, and its effects will be decided by a court.

New Berlin Rep. Mark Gundrum helped write the amendment, which he said is quite clear.

The amendment reads: "Only a marriage between one man and one woman shall be valid or recognized as a marriage in this state. A legal status identical or substantially similar to that of marriage for unmarried individuals shall not be valid or recognized in this state."

"Massachusetts clearly showed us why it's needed," Gundrum said. "Whether it's a creative term like civil unions in Vermont or civil covenants or state-sanctioned marriage, there will be a legal effort to get around the first sentence if we don't have the second sentence."

But opponents point to other states, where similar language is already part of the Constitution and court challenges are taking place.

In Ohio, some lower-court judges have ruled that domestic violence laws don't apply to unmarried people, but other Ohio courts disagreed.

In Michigan, the state Supreme Court has heard a case on the constitutionality of domestic partner benefits and is likely to rule soon.

Madison city attorney Michael May said the city's domestic partner benefits would be in question under the amendment -- not just for gay couples but also for unmarried straight couples currently covered under the benefits.

Those include health care reimbursement, discrimination protections and death benefits, May said.

"I concluded, on the balance of the arguments, it's more likely than not that we would probably lose those benefits here in Madison," May said. "A court could just as easily look at that and conclude that here's a legal right that Madison provides rights that are substantially similar to marriage and they could strike it down in that manner."

But attorney Michael Dean said he believes the amendment can allow for benefits.

"The argument that somehow this amendment will make it impossible to provide those benefits is simply not true," Dean said.

Dean represents eight local governments being sued by the ACLU to provide health benefits for gay couples.

"Clearly, individual governments can adopt any benefit programs they want that are not dependent on marital status or some kind of quasi-marital status," Dean said.

When asked if a domestic partnership is a quasi-martial status, Dean replied, "that all depends on how it's defined."

Dean said government, like Madison, could legally allow an employee to designate anyone for a benefit without tying it to a domestic partnership.

But if it were tied to who a person lives with and loves, the legal outcome would be up in the air, he said.

What is clear is that if the amendment passes, it will be challenged, experts said.

The authors of the amendment said it wouldn't cancel out the benefits.

"If there are lawsuits filed in regard to it, the lawsuits are going to come down the way I'm stating they're going to come down," Gundrum said. "That's just the way the legislation's been structured and that's clear in the legislative intent as well as in the language."

Gundrum said a big difference between Wisconsin's amendment and others is the wording. He said he believes that is the reason it will hold up in court without other effects.

But there are clearly differences of opinion on just what effects the amendment might have and how a court might rule.