California Code, Penal Code - PEN § 13653

(a) A peace officer, as defined in Section 830, may request an alleged law enforcement officer to present identification when there is probable cause or reasonable suspicion to believe the alleged law enforcement officer has committed a crime, including, but not limited to, impersonating a peace officer in violation of subdivisions (a), (b), or (c), of Section 538d.

(b) For purposes of this section, “law enforcement officer” includes a peace officer, as defined in Section 830, and any federal law enforcement officer.