Utah Code Ann. § 76-5-109
(1)
(a) As used in this section:
(ii) "Physical injury" means an injury to or condition of a child which impairs the physical condition of the child, including:
(iii)
(A) "Serious physical injury" means any physical injury or set of injuries that:
(B) "Serious physical injury" includes:
(2) An actor commits child abuse if the actor:
(3)
(4)
(c) An actor is not guilty of an offense under this section for conduct that constitutes:
(iii) the use of reasonable and necessary physical restraint or force on a child: