United States v. Lyons

Robert Lyons (defendant) was indicted on federal narcotics charges after becoming addicted to painkillers originally prescribed for legitimate medical conditions. He sought to introduce expert testimony that his addiction had physiologically and psychologically impaired his brain to the point that he lacked substantial capacity to conform his conduct to the law, raising an insanity defense under the volitional prong of the existing Model Penal Code test; the trial court excluded this evidence, and Lyons was convicted and appealed.