Utah Code § 76-1-502: Negating defense by allegation or proof -- When not required.

Section 76-1-501 does not require negating a defense:

(1) By allegation in an information, indictment, or other charge; or

(2) By proof, unless:

(a) The defense is in issue in the case as a result of evidence presented at trial, either by the prosecution or the defense; or

(b) The defense is an affirmative defense, and the defendant has presented evidence of such affirmative defense.