## Facts

- Robert Lyons, a physician, was charged with twelve counts of knowingly and intentionally obtaining controlled narcotics by misrepresentation, fraud, deception, or subterfuge, in violation of 21 U.S.C. § 843(a)(3) and 18 U.S.C. § 2.
- Lyons gave notice under Federal Rule of Criminal Procedure 12.2(a) that he would assert an insanity defense based on narcotics addiction.
- Lyons proffered evidence that prescribed narcotics for painful ailments led to addiction and that the addiction affected his brain physiologically and psychologically.
- Lyons offered expert testimony that, because of addiction-related effects, he lacked substantial capacity to conform his conduct to the law.
- The district court granted the government’s motion in limine and excluded evidence of Lyons’s drug addiction on the ground that addiction could not constitute a mental disease or defect supporting insanity.
- Lyons was convicted on all counts.
- A Fifth Circuit panel reversed, reasoning that the jury should decide whether involuntary addiction could qualify as a mental disease or defect under the insanity standard then used in the circuit.
- The Fifth Circuit granted rehearing en banc to reconsider both (1) addiction as a basis for insanity and (2) whether to retain the ALI/Model Penal Code insanity formulation.

## Issues

1. Whether narcotics addiction, standing alone (including addiction arising from prescribed medications), can constitute a “mental disease or defect” for purposes of the insanity defense.
2. Whether the circuit should retain the ALI/Model Penal Code insanity test’s volitional prong (inability to conform conduct) or limit insanity to a cognitive inquiry (inability to appreciate wrongfulness).
3. Whether Lyons’s proffered addiction-related evidence was admissible under the governing insanity standard.

## Decision

- The en banc Fifth Circuit rejected insanity based on “mere addiction” to narcotics, whether acquired voluntarily or involuntarily, absent other qualifying mental disease or defect.
- The court abandoned the ALI test’s volitional prong and adopted a cognitive-only rule: a defendant is not guilty by reason of insanity only if, at the time of the conduct, and as a result of mental disease or defect, the defendant was unable to appreciate the wrongfulness of the conduct.
- The court indicated Lyons should have an opportunity to present evidence to the extent it could support the cognitive prong (including evidence that addiction caused brain pathology amounting to a mental disease or defect).
- A dissent argued that excluding loss-of-control incapacity from the insanity defense permits punishment where the defendant lacked the ability to avoid the conduct.

## Legal Principles

- In the Fifth Circuit, legal insanity requires proof that, due to a mental disease or defect, the defendant was unable to appreciate the wrongfulness of the charged conduct.
- Inability to control conduct, by itself, is not a basis for insanity; the volitional prong of the ALI/Model Penal Code test is not part of the circuit’s insanity standard.
- Narcotics addiction alone is not a “mental disease or defect” for insanity purposes, even if the addiction originated involuntarily through medical treatment.
- Evidence that substance use or addiction produced a separate mental disease or defect (e.g., brain damage or comparable pathology) may be relevant, but only insofar as it bears on cognitive incapacity to appreciate wrongfulness.

## Conclusion

United States v. Lyons narrowed the insanity defense in the Fifth Circuit by adopting a cognitive-only test focused on appreciation of wrongfulness and by holding that addiction, without a separate qualifying mental disease or defect, cannot establish insanity, while allowing medically grounded proof of cognitive impairment to be presented when supported by evidence of resulting mental pathology.


United States v. Lyons, 731 F.2d 243 (5th Cir. 1984) (en banc)