ATLANTA, May 16 — A state amendment banning same-sex marriage was struck down Tuesday by a judge who upheld the voters' right to limit marriage to heterosexual couples but cited procedural flaws in the wording of the amendment, which was approved by more than three-quarters of voters.

The decision is one of the first successful challenges to a ban on same-sex marriage, one of a spate of similar amendments passed in 11 states in November 2004, said Jack Senterfitt, a senior staff lawyer in the Southern regional office of Lambda Legal, a national gay rights group.

Lambda Legal filed the suit along with the American Civil Liberties Union of Georgia. Besides Georgia, 18 states have such laws, a spokeswoman for Lambda Legal said.

The Georgia amendment defined marriage as between a man and a woman, banned same-sex civil unions and said that same-sex unions performed in other states would not be recognized. The judge, Constance C. Russell of Fulton County Superior Court, ruled that the amendment violated Georgia's single-subject rule, which limits each amendment put before voters to one topic.

"People who believe marriages between men and women should have a unique and privileged place in our society may also believe that same-sex relationships should have some place, although not marriage," the judge wrote. "The single-subject rule protects the right of those people to hold both views and reflect both judgments by their vote."

Mr. Senterfitt said he expected the ruling to be appealed.

Commentary:

Reverse this to see if it still makes sense. Assume the majority was gay. Would the gay majority have the right to ban straight marraige? Assume the majority is Christian. Do they have the right to ban other religions? Conservative judges are a plight on our democracy.