In the Prop 8 case, the 9th Circuit panel has decided to ask the California Supreme Court to answer a key question of state law.

The state law question is whether the official proponents Prop 8 have "authority to assert the State’s interest in the initiative’s validity... when the public officials charged with that duty refuse to do so."

This is the threshold standing question. Standing is a matter of federal constitutional law, but the 9th Circuit has apparently perceived an element of the issue to depend on state law, and it is seeking an authoritative interpretation of state law from the state's highest court.