By Laura Zuckerman
SALMON, Idaho (Reuters) - A U.S. federal judge struck down Idaho's ban on gay marriage on Tuesday, saying it relegated same-sex couples to a second-class status in violation of constitutional guarantees of equal protection under the law.
The ruling by U.S. Magistrate Judge Candy Dale was the latest in a string of decisions by federal judges against state bans on same-sex matrimony that, if upheld by higher courts, would sharply broaden access to marriage for U.S. gay couples.
Dale said her decision would go into effect on Friday at 9 a.m. local time, unless put on hold by a higher court.
Marriage rights have been extended to gay couples in 17 states and the District of Columbia in a trend that has gained momentum since the U.S. Supreme Court ruled last June that legally married same-sex couples nationwide are eligible for federal benefits.
That decision, which struck down part of the 1996 federal Defense of Marriage Act, has been cited by a number of federal judges, including Dale, in subsequent opinions overturning state bans on gay matrimony.
The Idaho lawsuit was brought in November by two lesbian couples whose out-of-state marriages were invalid in Idaho and two couples who sought to be married in Idaho but were denied licenses. The lawsuit named Idaho Governor C.L. "Butch" Otter and Ada County Clerk Chris Rich as defendants.
Otter on Tuesday vowed to appeal, arguing that Idaho voters had in 2006 "exercised their fundamental right" by approving an amendment to the state constitution defining marriage as the union of a man and a woman.
"Today's decision, while disappointing, is a small setback in a long-term battle that will end at the U.S. Supreme Court," Otter said in a statement.
Dale sided with the couples in finding that the state's marriage laws intentionally discriminate on the basis of sexual orientation and thus "do not survive any applicable level of constitutional scrutiny."
She dismissed claims by Idaho's governor that heterosexual marriage focused on children's welfare rather than the "emotional interests of adults" and protected religious liberty.
An attorney for the four lesbian couples who challenged Idaho's gay marriage ban said his clients and their children "are thrilled."
"This decision means so much to them and to other same-sex couples and families across the state, who have waited for decades to be treated as equal citizens," said Shannon Minter, legal director of the National Center for Lesbian Rights in San Francisco.
In Virginia, opponents of the state's ban on gay marriage told a U.S. appeals court on Tuesday that the prohibition discriminated against same-sex couples, while supporters said they considered it an appropriate defense of a traditional family model.
(Writing by Laura Zuckerman; Editing by Cynthia Johnston, Eric Walsh and Matt Driskill)