A US federal appeals court asked California's top tribunal on Tuesday to help it rule on a challenge by opponents of gay marriages in the western US state.
The US Ninth Circuit Court of Appeals sent the question back to California's Supreme Court, asking it to rule on whether anti gay marriage campaigners have the right to challenge a decision last year legalizing gay unions.
Supporters of so-called Prop 8 -- a 2008 referendum measure which banned gay marriage in California -- took their fight to the US federal court last month, in the latest stage of a legal saga that could have national implications.
Gay rights activists wanted the 9th US Circuit Court of Appeals to uphold a landmark ruling in August last year that overturned a ban on homosexual weddings in California.
But the federal appeals court said Tuesday it could not decide the case, and sought advice from California on whether those bringing the action -- as opposed to California authorities -- had the legal right to do so.
"We cannot consider this important constitutional question unless the appellants before us have standing to raise it ... It is critical that we be advised of the rights (of those taking the legal action) under California law."
In the August ruling, a federal judge said a ban on gays and lesbians tying the knot -- imposed by the 2008 referendum -- was discriminatory and therefore violated the US Constitution.
But opponents of gay weddings appealed, and a week later a federal judge agreed to maintain the ban pending the appeals process which started on December 6.
Critics argue that California's voters made their intentions known in the November 2008 ballot initiative known as Proposition 8, which imposed the ban on same-sex unions.
The proposal passed with a 52 percent majority, only six months after the state's Supreme Court reversed a previous ban on same-sex weddings -- sending gays and lesbians flocking to marry.
Some 18,000 homosexual couples tied the knot between May and November that year, when gay weddings were briefly allowed.
Experts believe the legal fight is almost certain to end up before the US Supreme Court in around 18 months, once appeals hearings in lower courts have run their course.
Currently only the states of Connecticut, Iowa, Massachusetts, New Hampshire and Vermont, as well as the US capital Washington, recognize gay marriage.