Utah Code Ann. § 41-6a-1501 – Motorcycle or motor-driven cycle -- Place for operator to ride -- Passengers.

(1) A person operating a motorcycle or motor-driven cycle shall ride only on the permanent and regular seat attached to the motorcycle or motor-driven cycle.
(2)
1. (a) Except as provided in Subsection (2)(b):
  1. (i) a person operating a motorcycle or motor-driven cycle may not carry any other person on the motorcycle or motor-driven cycle; and
  2. (ii) a passenger may not ride on a motorcycle or a motor-driven cycle.
2. (b) If a motorcycle or motor-driven cycle is designed to carry more than one person, a passenger may ride on:
  1. (i) the permanent and regular seat, if designed for two persons; or
  2. (ii) another seat firmly attached to the motorcycle or motor-driven cycle at the rear or side of the operator.
(3) A person shall ride on a motorcycle or motor-driven cycle only while sitting astride the seat, facing forward, with one leg on either side of the motorcycle or motor-driven cycle.
(4) A person may not operate a motorcycle or motor-driven cycle while carrying a package, bundle, or other article which prevents the person from keeping both hands on the handlebars.
(5) An operator of a motorcycle or motor-driven cycle may not carry a person and a person may not ride in a position that interferes with:
1. (a) the operation or control of the motorcycle or motor-driven cycle; or
2. (b) the view of the operator.
(6) A violation of this section is an infraction.