Utah’s New Rule Allowing Propensity Evidence in Sexual Assault Prosecutions

During the 2026 session, Utah’s legislature amended Utah’s rules of evidence, adding a new provision (subsection 404(d)). The new provision allows prosecutors to present to juries sexual assault propensity evidence in sexual assault cases. The Federal Rules of Evidence have contained a similar rule (Rule 413) for more than two decades. Numerous states follow comparable approaches—either through rule or caselaw—tracking the common law approach of admitting evidence to prove a “lustful disposition.” Utah’s rules will now benefit from a provision codifying this approach in Rule 404(d).

Because of the significance of this new rule change, I’ve written an article with Utah County prosecutor Ryan McBride explaining the rationale behind it and how it will operate in practice. The article makes four arguments in favor of the new rule.

First, because most sex crimes are committed by perpetrators against victims in private places, admitting evidence of similar crimes is often critical to a successful prosecution of those perpetrators. In light of frequently conflicting testimony from victims and defendants in sexual assault cases, admitting similar crimes evidence serves to arm the jury with more information from which to determine the truth and reach an accurate verdict. When the defendant claims to have been unjustly accused, allowing evidence of other acts of misconduct often puts an entirely different light on the matter. Combining direct evidence of guilt with evidence of the defendant’s past crimes may thus eliminate  reasonable doubt in a case that would otherwise be inconclusive. As Utah Senator Orrin Hatch concluded in co-sponsoring legislation adding Rule 413 to the Federal Rules of Evidence, the public interest in admitting evidence “that will illuminate the credibility of the charge and any denial by the defense is truly compelling.” Letter from Sen. Orrin G. Hatch, Rep. Susan Molinari, and Rep. John Kyl to Chief Justice William H. Rehnquist 2 (Oct. 11, 1994).

Second, historically Utah law recognized a similar crimes exception, only for that precedent to be obscured or ignored by what appears to have been sexist assumptions about the unreliability of women reporting sexual assaults. The history begins just a few years after Utah joined the Union in 1896. Four years later, in 1900, the Utah Supreme Court first addressed whether evidence of prior acts of sexual intercourse between the accused and the victim was admissible in a prosecution for statutory rape. State v. Hilberg, 61 P. 215 (Utah 1900), while noting the general prohibition against propensity evidence, also recognized that prior acts of intercourse between the parties (but not subsequent acts) were admissible to show the accused committed the crime charged. The Utah Supreme Court reached an identical conclusion the following year in State v. Neel, 65 P. 494 (Utah 1901), holding that evidence of prior sexual acts between parties was admissible to explain the acts in question.

A few years later, however, in 1909, the court appeared to depart from the rationale of Hilberg and Neel. In State v. Williams, 103 P. 250 (Utah 1909), a seventy-year-old man had been convicted of sexual assault on a ten-year-old girl and appealed. In overturning the conviction, the court held that a general prohibition against propensity evidence controlled. The court quoted Hilberg’s language about previous acts of “improper familiarity” making it “more probable” that the charged crime was committed but narrowed the application of this language to prior sexual conduct between the defendant and the victim of the charged offense. The court reasoned that the authorities “uniformly” hold that crimes “wholly disconnected from the crime charged on some person other than the one mentioned in the information or indictment is never admissible.” Id.

Williams clearly misstated the state of the law in this country. See, e.g., 3 Joel Prentiss Bishop, New Criminal Procedure § 970 at 1846 (2d ed. 1913); § 970 at 46 (1st ed. 1880) (explaining that in England such sexual predisposition evidence was not admissible, but “(t)he contrary to this, believed to be the better law, has been adjudged with us”). The court’s opinion curiously offered no reason for distinguishing the defendant’s prior sexual conduct with the victim of the charged offense from that with other victims. Nor did Williams attempt to reconcile its holding with Hilberg’s holding that prior sexual acts with the victim of a charged offense make subsequent sexual misconduct “more probable.”

The Williams decision seems so odd that perhaps its true rationale is reflected in its reference to the dictum from Lord Hale that rape of a woman “‘is an accusation easily made, hard to be proved, and still harder to be defended by one ever so innocent.”‘ Williams, 103 P. at 254 (quoting 3 Greenleaf Ev. § 212). This claim about false rape claims has now been thoroughly discredited; it reflects sexist notions about the untruthfulness of women who have come forward to report being sexually assaulted, as many commentators have explained. See, e.g., Vivian Berger, Man’s Trial, Woman’s Tribulation: Rape Cases in the Courtroom, 77 Colum. L. Rev. 1, 10–12 (1977) (noting that Hale’s admonition singles out rape for unique treatment and proposing to treat rape like other crimes). But the unfortunate effect of the poorly reasoned Williams decision was to overshadow the court’s earlier holdings to the contrary—as I have discussed in an earlier article. Utah’s new rule discards the discredited approach of the Williams decision and returns to the better-reasoned approach contained in Hilberg and Neel.

Third, a majority of jurisdictions in the United States now often allow the admission of similar crimes evidence in sexual assault cases. In a 1986 review of the issues, the U.S. Department of Justice concluded that  “free use of propensity evidence in prosecutions of sex crimes is widespread.” See generally Office of Legal Policy, U.S. Dep’t of Justice, Report to the Attorney General: The Admission of Criminal Histories at Trial at 10 (Aug. 14, 1986). While exact quantification of case law in multiple jurisdictions is always difficult, a fifty-state survey by Professor Thomas J. Reed in 1993 found that twenty-nine states “admit sexual misconduct evidence via the common-law lustful disposition rule.” Thomas J. Reed, Reading Gaol Revisited: Admission of Uncharged Misconduct Evidence in Sex Offender Cases, 21 Am. J. Crim. L. 127, 188 & n.340 (1993) (listing Utah as among the twenty-nine, based on Neel, discussed earlier). That rule, in short, is that “the prosecution in its case in chief could prove the defendant’s lustful disposition to commit sex crimes by proof of prior or later instances of sexual misconduct with the same victim or a different victim.” Even in states that did not follow a lustful disposition approach but instead applied Rule 404(b), the survey found that “the courts generally grant the prosecution great leeway to introduce uncharged sexual misconduct” evidence even when the other purpose besides propensity “is not truly an issue in the case.”

And, most important, in 1994, Congress simply followed this well-trodden path in adding a similar crimes rule into the Federal Rules of Evidence by adopting Rule 413. The federal rule was essentially a codification of the common law lustful disposition rule. See Basyle J. Tchividjian, Predators and Propensity: The Proper Approach for Determining the Admissibility of Prior Bad Acts Evidence in Child Sexual Abuse Prosecutions, 39 Am. J. Crim. L. 327, 341 (2012). As a result of the amendment to the Federal Rules of Evidence, the admission of propensity evidence in sexual assault cases has now expanded. The  current, i.e., 2019, Wigmore treatise on evidence notes the enactment of Rule 413 and  concludes that “recent developments in evidence law have rendered such evidence [i.e., evidence of uncharged misconduct in prosecutions for sex crimes,] more broadly admissible in many jurisdictions….” David P. Leonard, The New Wigmore: A Treatise on Evidence; Evidence of Other Misconduct and Similar Events § 8.5.3 (2d ed. 2019). The treatise hastened to emphasize, in addition, that even apart from specific rules of evidence, “courts have long approved admission of such evidence in sexual crime and child molestation cases.”

Fourth, my article explains how the language in the new Rule 404(d) will operate, drawing on other parallel state and federal rules that have been in operation for some time. Courts around the country have had difficulty in deciding whether something like the lustful  disposition rule survives Rule 404(b) or is abolished by it. See Reed at 186–88 (discussing conflicting interpretations in various state courts). The Utah Legislature has now ended any further possible confusion by simply adopting new Rule 404(d), which directly answers that question and permits similar sexual assault evidence to be admitted against a defendant for propensity purposes.

While new Utah Rule 404(d) makes propensity evidence presumptively admissible, it is important to note that the rule does not make it automatically admissible in every case.  Like other parts of Rule 404, the trial court must also apply Rule 403, which requires the exclusion of evidence in rare cases where the probative value of evidence is “substantially outweighed” by prejudicial effect.

In sum, as the article explains at greater length, the Utah Legislature has acted wisely in adopting new Evidence Rule 404(d), creating a presumption of admissibility for similar crimes evidence in sexual assault cases. In sexual assault cases where propensity evidence is available, prosecutors should seek to introduce that evidence, which will give Utah’s juries a fuller appreciation of all the circumstances. And the minority of states that still preclude propensity evidence in sexual assault cases should consider following the increasingly mainstream approach reflected in Utah’s new rule and the Federal Rules of Evidence.