(a) A person may not operate a truck, road tractor, or truck tractor when another person occupies a trailer or semitrailer being drawn by the truck, road tractor, or truck tractor.(b) It is a defense to prosecution under this section that:(1) the person was operating or towing the vehicle:(A) in a parade or in an emergency;(B) to transport farmworkers from one field to another field on a farm-to-market road, ranch-to-market road, or county road outside a municipality; or(C) in a hayride permitted by the governing body of or a law enforcement agency of each county or municipality in which the hayride will occur;(2) the person operating or towing the vehicle did not know that another person occupied the trailer or semitrailer; or(3) the person occupying the trailer or semitrailer was in a part of the trailer or semitrailer designed for human habitation.(c) An offense under this section is a Class B misdemeanor. Added by Acts 2003, 78th Leg., ch. 641, Sec. 1, eff. Sept. 1, 2003.