[KevinP73]

California Vehicle Code Section 40804
40804. (a) In any prosecution under this code upon a charge
involving the speed of a vehicle, an officer or other person shall be
incompetent as a witness if the testimony is based upon or obtained
from or by the maintenance or use of a speed trap.
(b) An officer arresting, or participating or assisting in the
arrest of, a person so charged while on duty for the exclusive or
main purpose of enforcing the provisions of Divisions 10 (commencing
with Section 20000) and 11 (commencing with Section 21000) is
incompetent as a witness if at the time of that arrest he was not
wearing a distinctive uniform, or was using a motor vehicle not
painted the distinctive color specified by the commissioner.
(c) This section does not apply to an officer assigned exclusively
to the duty of investigating and securing evidence in reference to
the theft of a vehicle or failure of a person to stop in the event of
an accident or violation of Section 23109 or 23109.1 or in reference
to a felony charge or to an officer engaged in serving a warrant
when the officer is not engaged in patrolling the highways for the
purpose of enforcing the traffic laws.