Vehicle Code § 21757

The driver of a vehicle shall not overtake and pass upon the left, nor shall any driver of a vehicle drive upon the left side of, any interurban electric or street car proceeding in the same direction whether the street car is actually in motion or temporarily at rest, except:

(a) When so directed by a police or traffic officer.

(b) When upon a one-way street.

(c) When upon a street where the tracks are so located as to prevent compliance with this section.