Cal. Penal Code § 538c

(a) Except as provided in subdivision (c), any person who attaches or inserts an unauthorized advertisement in a newspaper, whether alone or in concert with another, and who redistributes it to the public or who has the intent to redistribute it to the public, is guilty of the crime of theft of advertising services which shall be punishable as a misdemeanor. (b) As used in this section: (1) “Unauthorized advertisement” means any form of representation or communication, including any handbill, newsletter, pamphlet, or notice that contains any letters, words, or pictorial representation that is attached to or inserted in a newspaper without a contractual agreement between the publisher and an advertiser. (2) “Newspaper” includes any newspaper, magazine, periodical, or other tangible publication, whether offered for retail sale or distributed without charge. (c) This section does not apply if the publisher or authorized distributor of the newspaper consents to the attachment or insertion of the advertisement. (d) This section does not apply to a newspaper distributor who is directed to insert an unauthorized advertisement by a person or company supplying the newspapers, and who is not aware that the advertisement is unauthorized. (e) A conviction under this section shall not constitute a conviction for petty theft.