Supporters and opponents of California's ban on same-sex marriage were anxiously awaiting a federal appeals court decision Tuesday on whether the voter-approved measure violates the civil rights of gay men and lesbians.

A three-judge panel of the 9th U.S. Circuit Court of Appeals that considered the question plans to issue its long-awaited opinion 18 months after a trial judge struck down the ban following the first federal trial to examine if same-sex couples have a constitutional right to get married.

The 9th Circuit does not typically give notice of its forthcoming rulings, and its decision to do so Monday reflects the intense interest in the case.

Even if the panel upholds the lower court ruling, it could be a while before same-sex couples can resume marrying in the state. Proposition 8 backers plan to appeal to a larger 9th Circuit panel and then to the U.S. Supreme Court if they lose in the intermediate court. Marriages would likely stay on hold while that process plays out.

The three-judge panel, consisting of judges appointed by presidents Jimmy Carter, Bill Clinton and George W. Bush, heard arguments on the ban's constitutional implications more than a year ago. But it put off a decision so it could seek guidance from the California Supreme Court on whether Proposition 8 sponsors had legal authority to challenge the trial court ruling after California's attorney general and governor decided not to appeal it.