Cal. Government Code § 8670.27

(a) (1) All potentially responsible parties for an oil spill and all of their agents and employees and all state and local agencies shall carry out response and cleanup operations in accordance with the applicable contingency plan, unless directed otherwise by the administrator, the United States Coast Guard, or the United States Environmental Protection Agency. (2) Except as provided in subdivision (b), the responsible party, potentially responsible parties, their agents and employees, the operators of all vessels docked at a marine facility that is the source of a discharge, and all state and local agencies shall carry out spill response consistent with the California oil spill contingency plan or other applicable federal, state, or local spill response plans, and owners and operators shall carry out spill response consistent with their applicable response contingency plans, unless directed otherwise by the administrator, the United States Coast Guard, or the United States Environmental Protection Agency. (b) If a responsible party or potentially responsible party reasonably, and in good faith, believes that the directions or orders given by the administrator pursuant to subdivision (a) will substantially endanger the public safety or the environment, the party may refuse to act in compliance with the orders or directions of the administrator. The responsible party or potentially responsible party shall state, at the time of the refusal, the reasons why the party refuses to follow the orders or directions of the administrator. The responsible party or potentially responsible party shall give the administrator written notice of the reasons for the refusal within 48 hours of refusing to follow the orders or directions of the administrator. In any civil or criminal proceeding commenced pursuant to this section, the burden of proof shall be on the responsible party or potentially responsible party to demonstrate, by clear and convincing evidence, why the refusal to follow the orders or directions of the administrator was justified under the circumstances.