SAN FRANCISCO — The 9th U.S. Circuit Court of Appeals' decision to deny an appeal of February's ruling against Proposition 8 paves the way for a U.S. Supreme Court decision on same-sex marriage by next year.

The decision means the Supreme Court is likely to have two major gay-rights cases on its docket in the near future. Another federal appeals court last week struck down a federal law that denied federal recognition to same-sex marriage.

Backers of Proposition 8 said they would ask the Supreme Court to review the 9th Circuit ruling.

Proposition 8, passed by California voters in November 2008, reinstated a ban on same-sex nuptials six months after the state Supreme Court had struck it down on state constitutional grounds. The ballot measure amended the state constitution. Two same-sex couples then sued in federal court, contending that Proposition 8 violated the U.S. Constitution.

A three-judge panel ruled 2-1 in February that the ban violated federal constitutional guarantees but limited the effect of the ruling to California. Sponsors of Proposition 8 asked the 9th Circuit to assemble an 11-judge panel to rehear the case.

A majority of the circuit's active judges voted against such reconsideration.

On Tuesday, Judge Diarmuid O'Scannlain, joined by two other jurists, wrote in a dissent that President Barack Obama, in declaring his personal support for same-sex marriage, said it was a matter for states to decide.

"We have overruled the will of 7 million California Proposition 8 voters," O'Scannlain wrote. "We should not have so roundly trumped California's democratic process without at least discussing this unparalleled decision as an en banc court."

Judges Stephen Reinhardt and Michael Daly Hawkins, who voted in February to overturn Proposition 8, responded in a concurring opinion that their ruling was narrow.

"We held only that under the particular circumstances relating to California's Proposition 8, that measure was invalid. In line with the rules governing judicial resolution of constitutional issues, we did not resolve the fundamental question that both sides asked us to: whether the Constitution prohibits the states from banning same-sex marriage.

"That question may be decided in the near future, but if so, it should be in some other case, at some other time."

Online: An interactive map detailing gay marriage laws in the U.S.