California Code, Business and Professions Code - BPC § 17537.3

(a) For any person to offer as part of an advertising plan or program, promotional offers of smokeless tobacco products which require proof of purchase of a smokeless tobacco product unless it carries a designation that the offer is not available to persons under 21 years of age.  Each promotional offer shall include in any mail-in coupon a statement requesting purchasers to verify that the purchaser is 21 years of age or older.

(b) For any person to honor mail-in and telephone requests for promotional offers of smokeless tobacco products unless appropriate efforts are made to ascertain that a purchaser is over 21 years of age.  For purposes of this subdivision, appropriate efforts to ascertain the age of a purchaser includes, but is not limited to, requests for a purchaser's birth date.

(c) For any person by any means, as part of an advertising plan or program, to distribute free samples of smokeless tobacco products within a two-block radius of any premises or facilities whose primary purpose is directed toward persons under 21 years of age including, but not limited to, schools, clubhouses, and youth centers, when those premises are being used for their primary purposes.

(d) For any person to distribute, as part of any advertising plan or program, unsolicited samples of smokeless tobacco products through a mail campaign.