California Code, Government Code - GOV § 53080.5

(a) No city or county may require an applicant for a building or encroachment permit to file a certificate of insurance evidencing coverage for bodily injury or property damage liability as a condition to the issuance of either, or both, of those permits, unless the city or county imposes that requirement by ordinance.

(b) This section does not apply to contracts for public works of improvement entered into by a city or county.