Story highlights Series of court rulings prompt Nevada to stop defending ban against gay marriage

The state's arguments "are no longer sustainable," says attorney general

Governor adds the state's "case is no longer defensible in court," spokeswoman says

Lambda Legal, whose clients challenged ban, praises state's decision

Nevada won't defend its ban against same-sex marriage , saying its legal position has been "undermined" in a series of rulings that began last June with a historic U.S. Supreme Court ruling recognizing gay marriages.

The state's decision comes in a case filed by eight same-sex couples represented by the gay rights group Lambda Legal. The case challenged Nevada's constitutional amendment banning marriage for gay and lesbian couples, the group said.

A federal court judge dismissed the suit in 2012 at Gov. Brian Sandoval's request, but Lambda Legal appealed that ruling to the federal 9th Circuit Court of Appeals. Since then, the U.S. Supreme Court struck down a key part of the federal Defense of Marriage Act that had denied to legally married same-sex couples the same federal benefits provided to heterosexual spouses.

A subsequent 9th Circuit Court ruling in an unrelated case persuaded Nevada to abandon its defense of the gay marriage ban, Nevada officials said. That recent case involved a preemptory challenge to strike a prospective juror in a trial because he was gay, but the 9th Circuit ruled that discriminatory classifications based on sexual orientation must receive heightened scrutiny and should be presumed unconstitutional, Lambda Legal said.

"After thoughtful review and analysis, the state has determined that its arguments grounded upon equal protection and due process are no longer sustainable," Nevada Attorney General Catherine Cortez Masto said in a statement Monday.

Gov. Sandoval agreed with the attorney general's decision to drop its defense of the gay marriage ban.

"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," Mary-Sarah Kinner, a spokeswoman for the governor, said Tuesday.

A Lambda Legal attorney praised the governor's decision.

"The governor has recognized that the writing is on the wall, and that arguments seeking to perpetuate discrimination are becoming extremely difficult to justify," Lambda Legal Senior Attorney Tara Borelli said in a statement. "Denying marriage to same-sex couples serves no legitimate state interest and is intended solely to perpetuate discrimination."

The state's withdrawal leaves only the Coalition for the Protection of Marriage, which a lower court allowed to intervene, defending the marriage ban in federal appeals court, Lambda Legal said.

The coalition wasn't immediately available for comment Tuesday.