prop 8 is a prop that tried to leagalize gay marriage.
It wasn't legal, unless the marriage was solemnized before the passing of Prop 8. The license just gave you the right to marry, but the actual ceremony and having it registered is what makes it legal, and during the Prop 8 era, no weddings could be held. But if the marriage was registered, then you were legally married in California. You would have also been part of a lawsuit before the California Supreme Court.