Cal. FAC § 7

(a) Any person in whom the enforcement of any provision of this code is vested shall have the authority, as a public officer, to arrest, without a warrant, another person whenever such officer has reasonable cause to believe that the person to be arrested has, in his presence, violated any provision of this code, the violation of which is declared to be public offense. If such violation is a felony, or if the arresting officer has reasonable cause to believe that the person to be arrested has violated a provision of this code which is declared to be a felony, although no felony has in fact been committed, he may make an arrest although the violation or suspected violation did not occur in his presence.

In any case in which an arrest is made pursuant to this authority for an offense declared to be a misdemeanor or an infraction, the arresting officer may, instead of taking the person arrested before a magistrate, follow the procedure prescribed by Chapter 5C (commencing with Section 853.5) of Title 3 of Part 2 of the Penal Code, unless the arrested person demands to be taken before a magistrate. The provisions of such chapter shall thereafter apply with reference to any proceeding based upon the issuance of a citation pursuant to this authority.

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

(c) Any person in whom the enforcement of any provision of this code is vested may serve all processes and notices throughout the state; provided, that county employees authorized to enforce the provisions of this code are authorized to serve processes and notices only within the boundaries of the county which employs them.