Cal. INS § 10127

On and after January 1, 1974, every self-insured employee welfare benefit plan that provides coverage for hospital, medical, or surgical expenses shall offer coverage for expenses incurred as a result of mental or nervous disorders, under the terms and conditions which may be agreed upon between the self-insured welfare benefit plan and the member. If the terms and conditions include coverage for services provided in a general acute care hospital, or an acute psychiatric hospital as defined in Section 1250 of the Health and Safety Code, and do not restrict or modify the choice of providers, the coverage shall extend to care provided by a psychiatric health facility, as defined by Section 1250.2 of the Health and Safety Code, operating pursuant to licensure by the State Department of Health Care Services. Every plan shall communicate to prospective members as to the availability of outpatient coverage for the treatment of mental or nervous disorders. Every self-insured welfare benefit plan shall communicate the availability of this coverage to all members and prospective members. This coverage may include community residential treatment services, as described in former Section 5458 of the Welfare and Institutions Code, that are alternatives to institutional care.