Can courts exclude evidence of a confidential informant's post-offense arrest? State v. Swearingen Explained

The Utah Court of Appeals in State v. Swearingen addressed when trial courts may exclude evidence concerning a confidential informant’s criminal history, particularly arrests occurring after the alleged offenses but before trial. The decision emphasizes the critical importance of allowing defendants to impeach key prosecution witnesses for bias.

Background and Facts

Swearingen was charged with four counts of distributing controlled substances based on three undercover drug buys conducted by a confidential informant in 2019. The informant had an ongoing contract with law enforcement and was paid $100 per drug buy. Crucially, law enforcement did not observe the actual drug exchanges, and audio recordings were inconsistent and unclear, making the informant’s testimony the lynchpin of the prosecution’s case. In 2020, one year after the controlled buys but before Swearingen’s trial, the informant was arrested on drug possession charges, but no charges were filed.

Key Legal Issues

The central issue was whether the trial court properly excluded evidence of the informant’s 2020 arrest under the Utah Rules of Evidence. The State argued the evidence was irrelevant because the arrest occurred after the alleged drug buys and was inadmissible under Rule 609 because no charges resulted. The defense sought to introduce the evidence to demonstrate the informant’s ongoing bias and motive to misrepresent testimony to maintain his relationship with law enforcement.

Court’s Analysis and Holding

The court held that the trial court abused its discretion by excluding the evidence. The court analyzed admissibility under multiple rules: Rule 401 (relevance—bias evidence always meets the low relevance bar), Rule 608(c) (bias impeachment), Rule 403 (probative value substantially outweighs prejudice), and Rule 404(b) (admissible for non-character purpose of showing motive). The timing of the arrest was precisely what made it probative—the informant had ongoing contracts with law enforcement, no charges were filed, and the statute of limitations was still running at trial.

Practice Implications

This decision reinforces that impeachment for bias is fundamental to confrontation rights. When challenging exclusion of impeachment evidence, practitioners should argue admissibility under multiple evidentiary rules simultaneously. The court emphasized that when a witness is essential to the prosecution’s case, “the more latitude the defense should be given to explore fundamental elements such as motive, bias, or credibility.” The decision also demonstrates that post-offense conduct can be highly probative of bias when it shows ongoing relationships with law enforcement that could incentivize favorable testimony.