Cal. Health & Safety Code § 1367.20

Every health care service plan that provides prescription drug benefits and maintains one or more drug formularies shall provide to members of the public, upon request, a copy of the most current list of prescription drugs on the formulary of the plan by major therapeutic category, with an indication of whether any drugs on the list are preferred over other listed drugs. If the health care service plan maintains more than one formulary, the plan shall notify the requester that a choice of formulary lists is available.