Attorney General Catherine Cortez Masto, in a motion filed with the 9th U.S. Circuit Court of Appeals, said Nevada's legal arguments defending the voter-approved prohibition aren't viable after the court's recent ruling that potential jurors cannot be removed from a trial during jury selection solely because of sexual orientation.
"After thoughtful review and analysis, the state has determined that its arguments grounded upon equal protection and due process are no longer sustainable," Masto said in a statement.
Nevada's move comes as the federal government and courts around the country in recent months have chipped away at laws the prohibit marriage and benefits for same-sex couples. In a one-month span from December to January, two federal judges struck down state bans on gay marriage for the same reason, concluding that they violate the U.S. Constitution's promise of equal protection under the law.
Gov. Brian Sandoval, a Republican seeking re-election this year, said he agreed with the Democratic attorney general's action.
"Based upon the advice of the attorney general's office and their interpretation of relevant case law, it has become clear that this case is no longer defensible in court," Sandoval said in an email to The Associated Press.
The state's move was hailed by gay rights advocates and civil libertarians.
"This is fantastic evidence the state has recognized that equality for all people in Nevada and certainly across the country is of utmost importance," said Tod Story, executive director of the American Civil Liberties Union of Nevada.
The state's move was an about-face from January, when the attorney general's office filed a lengthy brief supporting the gay marriage ban that voters approved in 2002.
Eight same-sex couples, some married for decades, sued the state, arguing that the law is unconstitutional. A federal judge in Reno upheld the law in 2012, sending it to the appeals court in San Francisco.
One of the plaintiffs, Caren Jenkins, said she was delighted by the development, though it doesn't mean gaymarriages are imminent in Las Vegas' wedding chapels.
"This issue is far from resolved. The constitutionality issue still needs to be dealt with," Jenkins said. "But it certainly is something to celebrate."
Tara Borelli, senior attorney with Lambda Legal, a gay rights advocacy group that represented the couples, said Nevada's move is "a signal there's no longer any excuse to defend this discrimination."
"I think it will send a powerful message to the court that no Nevada official is willing to defend the ban any longer," she said.
Leaders with the Coalition for the Protection of Marriage, a conservative group that pushed for Nevada's gaymarriage ban, did not immediately respond to messages seeking comment.
In an initial brief supporting the law, the state argued that Nevada's constitutional amendment defining marriage as between a man and a woman is a legitimate state interest, "motivated by the state's desire to protect and perpetuate traditional marriage."
But the same day Nevada's brief was filed, a three-judge panel of the 9th Circuit issued a ruling in another case that changed the legal dynamics and left the attorney general's office immediately rethinking the state's position.
The court found that potential jurors could not be excluded from jury duty based on sexual orientation, extending to gays and lesbians a civil right that the U.S. Supreme Court has previously promised only to women and racial minorities.
Nevada lawmakers last year took the first step toward repealing the constitutional ban on gay marriage. If legislators approve Senate Joint Resolution 13 again next year, it would go to voters on the 2016 ballot.
Federal courts in other states have struck down similar bans, most recently in Utah and Oklahoma. Currently, 17 states allow gay marriage.
The Denver-based 10th U.S. Circuit Court of Appeals is reviewing the cases out of Utah and Oklahoma, with hearings scheduled for both in mid-April. Experts say the rulings could represent an emerging legal consensus that will carry the issue back to the Supreme Court.
Earlier Monday, the Justice Department began instructing its employees to give lawful same-sex marriages full and equal recognition to the greatest extent possible under the law. The policy announced over the weekend by Attorney General Eric Holder means same-sex spouses cannot be compelled to testify against each other, should be eligible to file for bankruptcy jointly, and are entitled to the same rights and privileges as federal prison inmates in opposite-sex marriages.
Holder cited the Supreme Court ruling in June that struck down a provision in the Defense of Marriage Act that defined marriage as the union of one man and one woman.
Associated Press writers Brady McCombs in Salt Lake City and Hannah Dreier in Las Vegas contributed to this report.