Utah Code § 41-6a-1706: Occupancy of a trailer or semitrailer while being moved on highway prohibited.

(1) A person may not occupy a trailer or semitrailer while it is being drawn by a motor vehicle on a public highway.

(2) This section does not apply to a:

(a) livestock trailer or livestock semitrailer;

(b) trailer or semitrailer being used for participation in a parade; or

(c) trailer or semitrailer being used in an agricultural operation.