Cal. INS § 11589

No insurer who provides professional liability insurance for physicians and surgeons or dentists shall increase the premium for such insurance, impose a surcharge with respect to such insurance, or otherwise require additional compensation for such insurance, or institute or increase a deductible amount payable by the insured, because a notice of intention to commence an action has been given pursuant to Section 364 of the Code of Civil Procedure, unless a complaint has been served on the physician and surgeon or dentist with respect to such action.

(b) For the purposes of this section, “professional liability insurance” means insurance against liability for damages caused by any act or omission of a physician and surgeon or dentist in rendering professional services within this state issued by any insurer, including, but not limited to, a joint underwriting association, cooperative corporation or reciprocal or interinsurance exchange.