California Code, Vehicle Code - VEH § 38604

(a) A person operating a recreational off-highway vehicle on lands, as described in Section 38001, shall not ride with a passenger, unless the passenger, while seated upright with their back against the seatback, can grasp the occupant handhold with the seatbelt and shoulder belt or safety harness properly fastened.

(b) For purposes of this chapter, “occupant handhold” means any factory or aftermarket device grasped by an occupant to provide support and to assist in keeping arms and hands within the recreational off-highway vehicle.  The steering wheel shall be considered an occupant handhold for the recreational off-highway vehicle operator.

(c) Occupant handholds shall be designed to allow the recreational off-highway vehicle passenger to exit the vehicle without interference from the handholds.