Updated 5:27 PM ET
(CBS/AP) SAN FRANCISCO - The sponsors of California's same-sex marriage ban said Tuesday they plan to ask the U.S. Supreme Court to review a landmark appellate court ruling that struck down the law as unconstitutional.
Alliance Defense Fund lawyer Brian Raum said Proposition 8 backers "absolutely" would take the case to the high court now that it has run its course at the 9th U.S. Circuit Court of Appeals.
Raum said he expected to get a ruling from the Supreme Court sometime in the fall on whether it would take the case. He did not know if the Proposition 8 defense team would take the entire 90 days they have to petition the Supreme Court.
Gay marriage supporters welcomed the latest news in the long-running legal battle. If the Supreme Court refuses to take up the case and lets the appellate ruling stand, same-sex marriages could be legal again in California by the end of the year.
If at least four justices agree to accept the case, oral arguments would likely be held next spring.
"The final chapter of the Proposition 8 case has now begun," said American Foundation for Equal Rights co-founder Chad Griffin, whose group is funding the effort to overturn the ballot measure. "Should the United States Supreme Court decide to review the 9th Circuit's decision in our case, I am confident that the justices will stand on the side of fairness and equality."
"This is a great step forward to the day when everyone will be able to marry the person they love," said attorney David Boies, who represents two couples who contested Prop 8, as reported by CBS San Francisco.
The move follows a federal appeals court's refusal to revisit a decision by two of its member judges declaring the voter-approved ban to be a violation of the civil rights of gays and lesbians in California.
Backers of the ban petitioned the full 9th U.S. Circuit Court of Appeals in February to review the decision instead of appealing directly to the U.S. Supreme Court.
Gay marriage opponents said at the time they would go to the high court if the appeals court declined to rehear the case.
Same sex unions were briefly legal in California before voters passed Proposition 8 in November 2008. Due to the ongoing legal wrangling, it's unlikely the practice will resume in the state anytime soon.
A majority of the 9th Circuit's 26 actively serving judges voted against giving the case a second look while leaving Proposition 8 in effect until a Supreme Court appeal is resolved.
Judge Diarmuid O'Scannlain issued a terse dissent, arguing that the full 9th Circuit should have reexamined its panel's 2-1 decision because in his view it was based on a "gross misapplication" of Supreme Court precedent and "overruled the will of seven million California voters." Judges Carlos Bea and Jay Bybee joined him in that opinion.
The 9th Circuit does not often agree to rehear cases, a procedure known as en banc review. Federal court rules reserve the practice for appeals that involve "a question of exceptional importance" or if the original decision appears to conflict with Supreme Court or 9th Circuit precedents.
Several other high-profile same-sex cases also are moving toward the high court. A three-judge panel of the Boston-based 1st U.S. Circuit Court of Appeals declared last week that the federal law that prohibits recognition of same-sex couples unconstitutionally denies Social Security and other federal spousal benefits to married gay couples.
The Massachusetts and California cases could reach justices at the same time, which "probably increases the likelihood the court will take the (Proposition 8) case," said Boies.
At the same time, because the 9th Circuit limited its decision to California instead of ruling that gay marriage bans are inherently unconstitutional, the Supreme Court might be inclined to let it stand, he said.