Cal. Gov. Code § 8635
The Legislature recognizes that if this state or nation were attacked by an enemy of the United States, many areas in California might be subjected to the effects of an enemy attack and some or all of these areas could be severely damaged. During such attacks and in the reconstruction period following such attacks, law and order must be preserved and so far as possible government services must be continued or restored. This can best be done by civil government. To help to preserve law and order and to continue or restore local services, it is essential that the local units of government continue to function.
In enacting this article the Legislature finds and declares that the preservation of local government in the event of enemy attack or in the event of a state of emergency or a local emergency is a matter of statewide concern. The interdependence of political subdivisions requires that, for their mutual preservation and for the protection of all the citizens of the State of California, all political subdivisions have the power to take the minimum precautions set forth in this article. The purpose of this article is to furnish a means by which the continued functioning of political subdivisions will be assured. Should any part of this article be in conflict with or inconsistent with any other part of this chapter, the provisions of this article shall control.
Nothing in this article shall prevent a city or county existing under a charter from amending said charter to provide for the preservation and continuation of its government in the event of a state of war emergency.
Ca. Gov. Code § 8635