Cal. Civ. Proc. Code § 764.070

Notwithstanding any other provision of this chapter, the judgment in the action is not binding or conclusive on the following:

(a) The state, unless individually joined as a party to the action.

(b) The United States, unless the United States is individually joined as a party to the action and federal law authorizes judgment in the action to be binding or conclusive as to its interests.