Updated

Kansans overwhelmingly voted to add a ban on gay marriage (search) and civil unions (search) to their state constitution, but both sides predicted court battles over the amendment.

The ban reaffirms the state's long-standing policy of recognizing only marriages between one man and one woman. It also declares that only such unions are entitled to the "rights and incidents" of marriage, prohibiting the state from authorizing civil unions for gay couples.

With final, unofficial results from 104 of the state's 105 counties on Tuesday, 414,235, or 70 percent, voted "yes," and 178,167, or 29 percent voted "no."

Critics argued the amendment could have unexpected consequences, such as potentially preventing companies from offering health benefits to employees' partners — gay or heterosexual.

The leader of a national group favoring the ban predicted Wednesday it ultimately will fail in federal court.

"All these state amendments are going to be struck down by federal judges," said Matt Daniels, president of the Alliance for Marriage (search). "We're in a race now — in a race between the democratic process in Kansas and other states and the federal courts."

Daniels' group has proposed an amendment to the U.S. Constitution to define marriage as a union between one man and one woman but leave to the states other issues, such as permitting civil unions. He said such a federal amendment is necessary to head off legal challenges to state amendments.

Matt Foreman, executive director of the National Gay and Lesbian Task Force (search), agreed that the U.S. Supreme Court ultimately will determine the validity of state constitutional bans on same-sex marriage.

Foreman predicted the amendment will spawn lawsuits as gays, lesbians and unmarried heterosexuals encounter problems.

"Does this impact living wills?" he asked. "Powers of attorney? Custody agreements? The enforcement of custody agreements?"

The Rev. Terry Fox, senior pastor of Wichita's Immanuel Baptist Church and a leader of the effort for the amendment, also predicted a legal attack by opponents but was confident the amendment would withstand scrutiny.

Voters in 13 states, including Missouri and Oklahoma, approved constitutional gay marriage bans last year, joining four others. Similar proposals will be on the ballot next year in Alabama, South Dakota and Tennessee.

Some Kansas voters, like 24-year-old Eric Hetzel, saw the amendment as a way to protect the traditional definition of marriage, written in Kansas law since 1867, from legal challenges.

"I am a Christian," Hetzel said. "I believe in the Bible and what it says that marriage is between a man and a woman."

But Byron Defreese, a 65-year-old retiree, called the amendment "total foolishness."

"I don't know how this is going to defend my marriage of 43 years," he said. "I think it's a diversion from the real issues."