## Facts

- Peter Elliot West robbed a bank in Champaign, Illinois; surveillance captured the robbery, and he was arrested shortly afterward with his mask, gun, and money.
- West’s sole defense was legal insanity under 18 U.S.C. § 17.
- The district court appointed Dr. Lawrence L. Jeckel, a board-certified psychiatrist, to examine West and report on his mental condition.
- Jeckel diagnosed West with a severe mental disease (schizoaffective disorder) but concluded West nevertheless understood the wrongfulness of his actions at the time of the robbery.
- Other mental-health evidence reflected serious psychiatric issues, including delusional beliefs and additional diagnoses from a federal medical center evaluation.

## Issues

1. Whether Fed. R. Evid. 704(b) permitted the district court to bar the defense from calling its appointed psychiatrist to testify about diagnosis, symptoms, and mental functioning in an insanity case.
2. Whether Fed. R. Evid. 403 justified exclusion of psychiatric testimony as confusing or misleading due to technical terminology.
3. Whether the evidence required an insanity instruction, despite mixed or conflicting psychiatric opinions.

## Decision

- The Seventh Circuit reversed the conviction and remanded for a new trial.
- The court held the district court misapplied Rule 704(b) by excluding the psychiatrist’s testimony wholesale rather than limiting only ultimate legal conclusions.
- The court held Rule 403 did not support exclusion because the testimony was highly probative to the only contested defense and any complexity could be managed through ordinary trial tools.
- The court held the refusal to instruct the jury on insanity, in conjunction with exclusion of the key psychiatric evidence, was reversible error.

## Legal Principles

- Fed. R. Evid. 704(b) prohibits experts from stating ultimate legal conclusions on a defendant’s insanity or legally defined mental state, but it permits testimony on diagnosis, symptoms, and the functional effects of mental illness.
- A defense expert is not excludable merely because aspects of the expert’s opinion are unfavorable to the defense theory; the jury may hear and weigh competent, relevant psychiatric evidence subject to proper limits.
- Under Fed. R. Evid. 403, psychiatric testimony central to an insanity defense generally should not be excluded as confusing solely because it uses specialized terminology when limiting instructions and examination can address clarity.
- When evidence provides a rational basis for a jury to find statutory insanity under 18 U.S.C. § 17, the defendant is entitled to an insanity instruction even if the psychiatric evidence is mixed.

## Conclusion

Because the insanity defense was the only plausible disputed issue and the district court improperly barred core psychiatric testimony and withheld an insanity instruction, the conviction was reversed and the case remanded for a new trial.


United States v. West, 962 F.2d 1243 (7th Cir. 1992)