When can Utah courts admit prior bad acts under the doctrine of chances? State v. Richins Explained

The Utah Supreme Court’s decision in State v. Richins provides crucial guidance on when courts may admit prior bad acts evidence under the doctrine of chances, establishing new requirements for prosecutors and clearer analytical frameworks for trial courts.

Background and Facts

Richins was charged with lewdness by a sex offender after a teenage neighbor reported seeing him masturbating in his yard. The testimony was equivocal—the witness said “it kind of looked like he might have been masturbating” but acknowledged “it’s possible that I saw his hands in his pocket.” To strengthen their case, prosecutors sought to introduce evidence of four prior incidents where different women accused Richins of similar public indecency. The district court admitted this evidence under the doctrine of chances to rebut claims of fabrication or mistake.

Key Legal Issues

The case addressed two critical issues: (1) whether the district court properly applied the doctrine of chances’ foundational requirements of materiality, similarity, independence, and frequency; and (2) whether the court conducted adequate rule 403 balancing between probative value and unfair prejudice when prior acts evidence creates both permissible probability-based inferences and impermissible propensity-based inferences.

Court’s Analysis and Holding

The Utah Supreme Court reversed, finding two fundamental errors. First, regarding the frequency requirement, the court held that district courts cannot rely solely on “intuition” to determine whether a defendant has experienced a rare misfortune more frequently than typical persons. Instead, courts must require evidence establishing a baseline frequency through testimony or judicial notice. Second, the court found that the district court failed to conduct proper rule 403 analysis by not weighing the probative value of permissible inferences against the substantial risk that jurors would draw impermissible propensity-based conclusions.

Practice Implications

This decision significantly raises the bar for doctrine of chances applications. Prosecutors must now present actual evidence—not just argument—to establish how frequently typical persons experience the alleged misfortune. Additionally, trial courts must explicitly balance competing inferences in their rule 403 analysis, weighing whether the jury is more likely to draw proper probability-based inferences or improper character-based inferences. The court emphasized that district courts should explain their reasoning with “precision of thought” to facilitate meaningful appellate review.