MUJI 2d CR501

As a general rule, if the evidence supports an affirmative defense, the State "has the burden to prove beyond a reasonable doubt" that the defense does not apply. State v. Knoll, 712 P.2d 211, 214-15 (Utah 1985). See also State v. Low, 2008 UT 58, para.45, 192 P.3d 867 (stating that murder instruction was in error "because it lacked the necessary element that the State show the absence of the affirmative defense[]."); State v. Swenson, 838 P.2d 1136, 1138 (Utah 1992) (stating that "a long line of Utah cases imposes on the prosecution the burden to disprove the existence of affirmative defenses beyond a reasonable doubt.") There are some exceptions to the general rule. The following list provides examples of statutes which allocate the burden of proof to the defendant, who must prove the affirmative defense by a preponderance of the evidence:

Utah Code Ann. § 58-37c-19.7(3)(c), Drug precursor statute (re: red phosphorus)

Utah Code Ann. § 58-37c-20(3)(c), Drug precursor statute (re: pseudoephedrine)

Utah Code Ann. § 58-37-8(12)(d), Ceremonial use of peyote by Native Americans statute

Utah Code Ann. § 19-5-115(5)(e), Environmental code violations

Although not specifically characterized as an affirmative defense, there is a provision in Utah Code Ann. § 76-5-401(3), Unlawful Sexual Activity with a Minor, which operates similarly. If a defendant establishes by a preponderance of the evidence that he was less than 4 years older than the minor, it reduces the offense from a third degree felony to a class B misdemeanor.