Court hears arguments over whether undercover detective’s testimony crossed from fact into expert opinion

The Utah Court of Appeals heard argument in State v. Hernandez over whether portions of detective testimony should have been excluded as improper expert opinion or legal conclusions. Defense counsel argued that Detective Rupp’s descriptions went beyond lay recollection and effectively told the jury the legal result (that the defendant "agreed" to a *** act in exchange for money), and that testimony about "typical John behavior" amounted to anecdotal profiling without statistical foundation.

Defense counsel told the court the testimony "pushed it much further" when the detective characterized the encounter in legal terms and said she recorded the event because "the criminal act had been committed." The panel asked how to draw a clean line between fact testimony describing a conversation and expert testimony opining about the defendant’s mental state. Counsel relied on precedent warning against experts reaching into a defendant’s mind and emphasized the risk that anecdotal profiling could fill gaps in thin prosecution proof.

The State (Chelsea Kenny) replied that the majority of Detective Rupp’s testimony was lay recounting of a conversation and conduct — what she observed and how the interview proceeded — and that references to typical conduct were contextual comparisons, not assertions about the defendant’s mens rea. The State further argued that testimony explaining undercover procedures and safety measures had probative value and provided necessary foundation for why officers acted as they did.

Both the panel and counsel discussed Rule 701–704 and Rule 403 tradeoffs: judges asked whether describing ‘‘agreement’’ necessarily invades mens rea and whether repeated testimony about undercover danger risked unfair prejudice. After rebuttal the court took the case under advisement and said it would issue an opinion when ready.