State v. Jesse, 362 P.3d 1187

Defendant was convicted of first-degree sexual abuse for allegedly touching his daughter over her diaper; prosecution relied heavily on defendant’s statements to his wife, statements to a jail deputy, and the child’s CARES interview.
Defendant had attended 15 therapy sessions with psychologist Dr. Callum, who diagnosed an adjustment disorder with depressed mood and described poor coping skills, rumination, and obsessive thinking.
Wife produced a signed written statement in which defendant purportedly admitted touching the child; defendant later disputed seeing the document and testified his signature was forged.
Defendant also made jailhouse statements to deputies saying, "I did it. I confess," which he later could not fully explain at trial.
Before trial, the state moved to exclude Callum’s testimony under OEC 702 for lack of a sufficient nexus between the diagnosis and the contested behaviors; the trial court excluded testimony about the diagnosis and psychological profile.
On appeal, the court considered whether the exclusion was erroneous under OEC 702 and whether any error was harmless, given the centrality of defendant’s statements to the state’s case.

Issue	State's Argument	Defendant's Argument	Held
Admissibility of expert testimony under OEC 702 (nexus/helpfulness)	Callum’s diagnosis lacks a demonstrated nexus to defendant’s statements/behavior; testimony is not helpful to the jury	Callum’s diagnosis explains rumination and poor coping that could produce false/confused admissions and signing the written statement; testimony is directly tied to the defense theory	Court reversed: exclusion was error — record established a nexus and the testimony would have assisted the jury
Harmless error (whether exclusion affected verdict)	Exclusion harmless because defendant testified inconsistently with defense theory and other evidence supported conviction	Exclusion not harmless because defendant’s statements were central to the state’s case and Callum’s testimony could have supported the defense explanation for those statements	Court held error was not harmless and reversed and remanded

State v. Nichols, 252 Or. App. 114 (Or. App.) (expert diagnosis inadmissible where no explanation linking diagnosis to behavior)
State v. Gherasim, 329 Or. 188 (Or.) (expert testimony admissible where it explained impairment affecting behavior/memory)
State v. O’Key, 321 Or. 285 (Or.) (discussion of OEC 702 helpfulness functions for expert testimony)
State v. Stringer, 292 Or. 388 (Or.) (OEC 702 threshold: expert testimony must assist the trier of fact)