California Code, Government Code - GOV § 54982

(b)(1) A city that provides law enforcement services through its appropriate departments, boards, commissions, officers, or employees to another city pursuant to a contract or any other agreement authorized by this chapter shall charge that city all the costs that are incurred in providing those law enforcement services, but shall not include any costs that the city providing the services reasonably determines are general overhead costs.

(2) For purposes of this section, “general overhead costs” means those costs that a city would incur regardless of whether or not it provided law enforcement services pursuant to a contract or agreement to the other city.

(3) Any determination of general overhead costs made by a city providing law enforcement services shall be subject to judicial review as to the reasonableness of that determination.

(4) This subdivision shall only apply to contracts or agreements entered into, or renewed, on and after January 1, 2017.