California Code, Health and Safety Code - HSC § 1367.2

(a) On and after January 1, 1990, every health care service plan that covers hospital, medical, or surgical expenses on a group basis shall offer coverage for the treatment of alcoholism under such terms and conditions as may be agreed upon between the group subscriber and the health care service plan. Every plan shall communicate the availability of such coverage to all group subscribers and to all prospective group subscribers with whom they are negotiating.

(b) If the group subscriber or policyholder agrees to such coverage or to coverage for treatment of chemical dependency, or nicotine use, the treatment may take place in facilities licensed to provide alcoholism or chemical dependency services under Chapter 2 (commencing with Section 1250) of Division 2.