Because the recent Ruling in DOMA last month said over and over that states get to choose on gay marriage, stating therefore at the same moment that gay marriage is not a constitutional right, a new case has been filed that will test this.
In spite of what you may have heard, DOMA in total was not "struck down" last month. Only one part of it was, where the fed has to abide by what the Court calls "the states' unquestioned authority" to decide on gay marriage.
Actually, DOMA was struck down in total. The decision means the federal government must recognize any gay marriage recognized by a state. If a state has legalized gay marriage, the federal government must extend all the federal cash and prizes to same sex marriages performed in that state which it extends to opposite sex marriages.
So that means all 50 states get to choose "no" on gay marriage if they like as their constitutional guarantee. The Court just interpreted that.
That means, that Prop 8 and the California iniative system that duly enacted that law have been under illegal attack by the Governor there, Jerry Brown and others.
The case is an injunction filed to stop bogus marriage licenses being issued to gay people under the misconception that Gov. Brown has the authority over the state initiative system. He doesn't. He is merely a public servant charged with upholding state law, not dictating it against the Will of the majority 7 million who voted for Prop 8.
So Gov. Brown ordered the County Clerks to issue marriage licenses in violation of law. Only Los Angeles and Alameda were excepted in the weird vague "Opinion" on the rat's nest that is the original Prop 8 hearing at the State Supreme Court. The other counties are still bound to abide by state law: which the Supreme Court just said was legal by virtue of their statement that states get to decide with their "unquestioned authority".
Actually, Prop 8 was overturned by the Ninth Circuit Court. By the US Supreme Court refusing to hear the case, that last decision by the Ninth Circuit stands. Prop 8 is struck down.
Gay marriages performed in California are consequently valid.