California Code, Vehicle Code - VEH § 21754

(a) When the vehicle overtaken is making or about to make a left turn.

(b) Upon a highway within a business or residence district with unobstructed pavement of sufficient width for two or more lines of moving vehicles in the direction of travel.

(c) Upon any highway outside of a business or residence district with unobstructed pavement of sufficient width and clearly marked for two or more lines of moving traffic in the direction of travel.

(d) Upon a one-way street.

(e) Upon a highway divided into two roadways where traffic is restricted to one direction upon each of such roadways.

The provisions of this section shall not relieve the driver of a slow moving vehicle from the duty to drive as closely as practicable to the right hand edge of the roadway.