California Code, Business and Professions Code - BPC § 5536.1

(a) All persons preparing or being in responsible control of plans, specifications, and instruments of service for others shall sign those plans, specifications, and instruments of service and all contracts therefor, and, if licensed under this chapter, shall affix a stamp, which complies with subdivision (b), to those plans, specifications, and instruments of service, as evidence of the person's responsibility for those documents.  The failure of any person to comply with this subdivision is a misdemeanor punishable as provided in Section 5536.  This section shall not apply to employees of persons licensed under this chapter while acting within the course of their employment.

(b) For the purposes of this chapter, any stamp used by any architect licensed under this chapter shall be of a design authorized by the board, which shall at a minimum bear the licensee's name, their license number, the legend “licensed architect” and the legend “State of California,” and which shall provide a means of indicating the renewal date of the license.

(c) The preparation of plans, specifications, or instruments of service for any building, except the buildings described in Section 5537, by any person who is not licensed to practice architecture in this state, is a misdemeanor punishable as provided in Section 5536.

(d) The board may adopt regulations necessary for the implementation of this section.