It is unlawful for any person to disobey the traffic directions of a person appointed or authorized by a local authority to regulate traffic pursuant to subdivision (e) of Section 21100 when such appointee is wearing an official insignia issued by the local authority and is acting in the course of his appointed duties.
Source:
Section 21100.3, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=21100.3..