MIAMI - A Florida law that has banned adoptions by gay men and lesbians for over three decades is unconstitutional, a judge here ruled on Tuesday.
"The best interests of children are not preserved by prohibiting homosexual adoption," the judge, Cindy S. Lederman of Miami-Dade Circuit Court, said in a 53-page decision. She said the law violated equal protection rights for children and their prospective parents.
A spokeswoman for the attorney general's office said the state would appeal, and the case is likely to end up before the State Supreme Court.
Florida is the only state with a law prohibiting gay men and lesbians - couples and individuals - from adopting children. The Legislature voted to prohibit adoptions by gay men and lesbians in 1977, in the midst of a campaign led by the entertainer Anita Bryant to repeal a gay rights ordinance adopted by Dade County.
In 2005, the United States Supreme Court refused to hear a challenge to the Florida law.
Some states, like Mississippi and Utah, effectively bar adoptions by same-sex couples through laws that prohibit adoption by unmarried couples. Arkansas voters passed a similar measure this month.
The ruling on Tuesday will allow Frank Martin Gill, 47, a gay man from North Miami, to adopt two foster children whom he has raised since 2004. "Our family just got a lot more to be thankful for this Thanksgiving," Mr. Gill said in a news release issued by the American Civil Liberties Union, which represented him.
Robert Rosenwald, director of the LGBT Advocacy Project of the American Civil Liberties Union of Florida and one of the lawyers on the case, said, "The case means that these two boys won't be torn from the only home that they've ever known," said.
The state presented experts who argued that there was a higher incidence of drug and alcohol abuse among same-sex couples, that their relationships were less stable than those of heterosexuals, and that their children suffered a societal stigma.
But lawyers for Mr. Gill presented evidence contradicting those contentions, which Judge Lederman found persuasive.
"It is clear that sexual orientation is not a predictor of a person's ability to parent," she wrote.
Mr. Rosenwald called the decision a huge victory for gay and lesbian parents and for almost 1,000 children in Florida waiting to be adopted.
"The court for the first time after hearing all of the evidence determined that the scientific evidence is crystal clear," he said. "There is no dispute that children raised by gay parents fare just as well or better than children raised by straight parents."