Cal. Vehicle Code § 21228

Any person operating a motorized scooter upon a highway at a speed less than the normal speed of traffic moving in the same direction at that time shall ride as close as practicable to the right-hand curb or right edge of the roadway, except under the following situations: (a) When overtaking and passing another vehicle proceeding in the same direction. (b) When preparing for a left turn, the operator shall stop and dismount as close as practicable to the right-hand curb or right edge of the roadway and complete the turn by crossing the roadway on foot, subject to the restrictions placed on pedestrians in Chapter 5 (commencing with Section 21950). (c) (1) When reasonably necessary to avoid conditions, including, but not limited to, fixed or moving objects, vehicles, bicycles, pedestrians, animals, surface hazards, or substandard width lanes, which make it unsafe to continue along the right-hand curb or right edge of the roadway, subject to Section 21656. (2) For the purposes of paragraph (1), a “substandard width lane” is a lane that is too narrow for a motorized scooter and another vehicle to travel safely side by side within the lane. (d) Any person operating a motorized scooter upon a highway that carries traffic in one direction only and has two or more marked traffic lanes may operate the motorized scooter as near the left-hand curb or left edge of that roadway as practicable. However, when preparing for a right turn, the operator shall stop and dismount as close as practicable to the left-hand curb or left edge of the highway and complete the turn by crossing the roadway on foot, subject to the restrictions placed on pedestrians in Chapter 5 (commencing with Section 21950).