Cal. Civ. Code § 1798.199.50

No finding of probable cause to believe this title has been violated shall be made by the agency unless, at least 30 days prior to the agency’s consideration of the alleged violation, the business, service provider, contractor, or person alleged to have violated this title is notified of the violation by service of process or registered mail with return receipt requested, provided with a summary of the evidence, and informed of their right to be present in person and represented by counsel at any proceeding of the agency held for the purpose of considering whether probable cause exists for believing the person violated this title. Notice to the alleged violator shall be deemed made on the date of service, the date the registered mail receipt is signed, or if the registered mail receipt is not signed, the date returned by the post office. A proceeding held for the purpose of considering probable cause shall be private unless the alleged violator files with the agency a written request that the proceeding be public.