California Code, Vehicle Code - VEH § 21809

(a) A person driving a vehicle on a highway approaching a stationary authorized emergency vehicle that is displaying emergency lights, a stationary tow truck that is displaying flashing amber warning lights, or a stationary marked Department of Transportation vehicle that is displaying flashing amber warning lights, shall approach with due caution and, before passing in a lane immediately adjacent to the authorized emergency vehicle, tow truck, or Department of Transportation vehicle, absent other direction by a peace officer, proceed to do one of the following:

(b) A violation of subdivision (a) is an infraction, punishable by a fine of not more than fifty dollars ($50).

(c) The requirements of subdivision (a) do not apply if the stationary authorized emergency vehicle that is displaying emergency lights, the stationary tow truck that is displaying flashing amber warning lights, or the stationary marked Department of Transportation vehicle that is displaying flashing amber warning lights is not adjacent to the highway or is separated from the highway by a protective physical barrier.