(Creative Commons)

Prop. 8, which bans gay marriage in California, passed with 52 percent of the vote in 2008.

A federal judge in San Francisco ruled the ban unconstitutional in August 2010, "saying it unfairly targeted gay men and women, handing supporters of such unions a temporary victory in a legal battle that seems all but certain to be settled by the Supreme Court."

When the state of California--then-Gov. Arnold Schwarzenegger and then-Attorney General Jerry Brown--decided not to appeal the San Francisco judge's ruling, Prop. 8 supporters looked elsewhere to find someone to file an appeal.

"The private citizens who organized Prop.8 were allowed to intervene on its behalf during the district court proceedings, including a civil trial. But gay rights attorneys challenging the ballot measure on appeal argued that only the state could defend the measure because it was a state law," reports Washington Blade, an LGBTQ news source.

The group, known as Project Marriage, filed an appeal with the 9th Circuit Court of Appeals. But this led to the "sticky legal question: 'Can Project Marriage speak for the state?'"

The appeals court turned to the California Supreme Court and said it would "accept and follow" the high court's decision on the procedural question.

"[W]hether state law enables supporters of a ballot measure to defend it in court when state officials refuse to" is the question the state's highest court will debate.

Oral arguments are expected to begin no earlier than September.

What comes next depends on whether the state's highest court rules that Prop. 8 supporters had the right to file the appeal since the state officials (Schwarzenegger and Brown) would not.

The Christian Science Monitor reports, "If the California Supreme Court decides that Protect Marriage does have standing, the Ninth Circuit will rule on the central issue of the case: Do gay couples have a right to marry? Since the circuit court has authority over more than just California, the ruling would be legally binding in 11 states and territories, from Guam to Montana. A Ninth Circuit decision would also tee up the case for the US Supreme Court. If the California Supreme Court decides that the group does not have standing, Judge Walker’s ruling will remain in place, lifting the stay that was put in place during the appeal and allowing gay weddings to proceed."