## Facts

- Bridget M. Denny-Shaffer, a labor and delivery nurse in New Mexico, was diagnosed by experts for both sides with multiple personality disorder (MPD) associated with severe childhood abuse.
- On May 10, 1991, she entered a hospital nursery in Las Cruces, New Mexico wearing a lab jacket, identified herself as a medical student, and examined infants.
- While unobserved, she took an infant (Kevin Daniel Chavez), concealed him, left the hospital, and drove out of state.
- She traveled to Texas and arrived at the home of a former boyfriend, later telling him the baby was his.
- Expert testimony agreed an alter personality, not Denny-Shaffer’s host personality, controlled her conduct during the taking and transportation of the infant.
- An expert indicated the insanity outcome could differ depending on whether the legal test evaluated only the controlling alter’s capacity to appreciate wrongfulness or considered the defendant’s overall condition, including the host’s awareness and control.

## Issues

1. Whether Denny-Shaffer produced sufficient evidence under 18 U.S.C. § 17(a) to warrant an insanity instruction, making it error for the trial court to withhold the defense from the factfinder.
2. In an MPD case, whether § 17(a) permits limiting the insanity inquiry solely to the alter personality controlling the criminal act, rather than assessing the defendant as a whole person, including the host personality’s awareness and control.

## Decision

- The court of appeals reversed the conviction and remanded for further proceedings.
- The trial court erred by concluding, as a matter of law, that the insanity evidence was insufficient and by refusing to instruct on insanity.
- MPD was treated on this record as a “severe mental disease or defect” within § 17(a).
- The trial court’s approach—evaluating only the controlling alter’s ability to appreciate wrongfulness—was too restrictive because it excluded evidence that the host personality may have been unaware of, and not in control of, the kidnapping.
- Denny-Shaffer met her burden of production to raise insanity; whether she satisfied her burden of persuasion by clear and convincing evidence was for the factfinder.

## Legal Principles

- A defendant is entitled to an insanity instruction when evidence is sufficient to permit a reasonable factfinder to find insanity under 18 U.S.C. § 17(a).
- Under § 17(a), the relevant inquiry is whether “the defendant,” due to a severe mental disease or defect, was unable to appreciate the nature and quality or wrongfulness of the acts; the statute does not require treating only a controlling alter as the “defendant.”
- In MPD cases, the insanity analysis may require considering the relationship between host and alter personalities, including evidence of the host’s contemporaneous awareness and control during the offense.
- The clear-and-convincing burden under § 17(b) governs persuasion at trial; it does not permit a court to remove the defense from the factfinder when the defendant has met the threshold burden of production.

## Conclusion

The conviction was reversed because the evidence of MPD and the host personality’s possible lack of awareness and control was sufficient to require submission of the federal insanity defense to the factfinder, and the trial court’s refusal to instruct on insanity improperly foreclosed that determination.


United States v. Denny-Shaffer, 2 F.3d 999 (10th Cir. 1993)