Cal. Health & Safety Code § 11111

A person, corporation, or retail distributor that sells or makes available products containing dextromethorphan, as defined in subdivision (a) of Section 11110, in an over-the-counter sale without a prescription shall, if feasible, use a cash register that is equipped with an age-verification feature to monitor age-restricted items. The cash register shall be programmed to direct the retail clerk making the sale to request bona fide evidence of majority and identity, as described in subdivision (c) of Section 11110, before a product containing dextromethorphan may be purchased.