California Code, Penal Code - PEN § 836.5

(a) A public officer or employee, when authorized by ordinance, may arrest a person without a warrant whenever the officer or employee has reasonable cause to believe that the person to be arrested has committed a misdemeanor in the presence of the officer or employee that is a violation of a statute or ordinance that the officer or employee has the duty to enforce.

(b) There shall be no civil liability on the part of, and no cause of action shall arise against, any public officer or employee acting pursuant to subdivision (a) and within the scope of his or her authority for false arrest or false imprisonment arising out of any arrest that is lawful or that the public officer or employee, at the time of the arrest, had reasonable cause to believe was lawful. No officer or employee shall be deemed an aggressor or lose his or her right to self-defense by the use of reasonable force to effect the arrest, prevent escape, or overcome resistance.

(c) In any case in which a person is arrested pursuant to subdivision (a) and the person arrested does not demand to be taken before a magistrate, the public officer or employee making the arrest shall prepare a written notice to appear and release the person on his or her promise to appear, as prescribed by Chapter 5C (commencing with Section 853.5). The provisions of that chapter shall thereafter apply with reference to any proceeding based upon the issuance of a written notice to appear pursuant to this authority.

(d) The governing body of a local agency, by ordinance, may authorize its officers and employees who have the duty to enforce a statute or ordinance to arrest persons for violations of the statute or ordinance as provided in subdivision (a).

(e) For purposes of this section, “ordinance” includes an order, rule, or regulation of any air pollution control district.

(f) For purposes of this section, a “public officer or employee” includes an officer or employee of a nonprofit transit corporation wholly owned by a local agency and formed to carry out the purposes of the local agency.