LINCOLN, Neb. — A federal judge Thursday struck down Nebraska's ban on gay marriage, saying the measure interferes not only with the rights of gay couples but also with those of foster parents, adopted children and people in a host of other living arrangements.

It was the first time a federal judge has overturned a state constitutional ban on same-sex marriage.

The Nebraska amendment, like Utah's, banned same-sex marriage and other domestic partnerships. The amendments, however, are worded differently.

U.S. District Judge Joseph Bataillon said the Nebraska ban "goes far beyond merely defining marriage as between a man and a woman."

The judge said it "imposes significant burdens on both the expressive and intimate associational rights" of gays "and creates a significant barrier to the plaintiffs' right to petition or to participate in the political process."

Forty states have Defense of Marriage laws, but Nebraska's was the only one that prevented homosexuals who work for the state or the University of Nebraska system from sharing health insurance and other benefits with their partners.

Bill Duncan, director of the Provo-based Marriage Law Foundation, called the decision "extremely broad" and "startling," but added that Utah's Amendment 3, which voters approved last November, was crafted to avoid being overly broad.

"I think Amendment 3 is still safe," he said, noting it applies only to relationships that are identical or "substantially similar" to marriage.

Dani Eyer, executive director of the Utah American Civil Liberties Union, said the Nebraska amendment "was the most extensive anti-gay-union law in the country. . . . It was designed to cut gay couples off from any sort of protection."

Nebraska has no state law against gay marriage, but state Attorney General Jon Bruning said same-sex marriages were not allowed before the ban and won't be permitted now.

Bruning said he will appeal the ruling.

The challenge was filed by the gay rights organization Lambda Legal and the ACLU's Lesbian and Gay Project.

In Utah, opponents of Amendment 3 had raised fears that the amendment would deny same-sex couples the right to petition their lawmakers for basic rights.

Attorney General Mark Shurtleff said in an Aug. 6, 2004, statement that its wording could strip away many fundamental rights for parents and their children in common-law marriages and other relationships during death, disability or breakups.

"It could forever deny a group of citizens the right to approach its legislature to seek benefits and protections," Shurtleff said in the statement.