In the order asking the Supreme Court to review the issue, the 9th Circuit wrote: "Although the governor has chosen not to defend Proposition 8 in these proceedings, it is not clear whether he may, consistent with the California constitution, achieve through a refusal to litigate what he may not do directly: effectively veto the initiative by refusing to defend or appeal a judgment invalidating it."

Proposition 8 supporters urged the state Supreme Court in a recent letter to tackle the question. Lawyers for same-sex couples said Wednesday they believe the state Supreme Court will eventually reject the right of a private group to defend a state law that the governor and attorney general deem unconstitutional.

This will be the fourth time in the past seven years that the state Supreme Court has been thrust into the state's gay marriage battleground. The court voided thousands of same-sex marriages issued by the city of San Francisco in 2004. The justices in 2008 struck down California's previous laws banning same-sex marriage, but then upheld Proposition 8 the following year, finding they could not invalidate a voter-approved amendment to the state constitution.