California Code, Vehicle Code - VEH § 27316.5

(a) Unless specifically prohibited by the National Highway Traffic Safety Administration, all type 2 school pupil activity buses, manufactured on or after July 1, 2004, purchased or leased for use in California shall be equipped at all designated seating positions with a combination pelvic and upper torso passenger restraint system.

(b) For purposes of this section, a “passenger restraint system” is either of the following:

(c) No person, school district, or organization, with respect to a type 2 school pupil activity bus equipped with passenger restraint systems pursuant to this section, may be charged for a violation of this code or any regulation adopted thereunder requiring a passenger to use a passenger restraint system, if a passenger on the school pupil activity bus fails to use or improperly uses the passenger restraint system.