Psychopathy rarely forms the basis of an insanity defense, due to its highly prejudicial nature. However, certain characterizations and types of evidence can somewhat reduce this stigma. Undergraduate participants (N = 270) in this mock trial experiment read vignettes describing a fictional murder case in which an insanity defense was raised. These vignettes varied by evidence type (neuroscientific or psychological) and by the defendant’s diagnosis (psychopathy, a brain disease, or psychosis). Participants delivered verdicts and answered questions about sentencing and their perceptions of the defendant. The results indicate that neuroscientific evidence is superior to psychological evidence in establishing a successful insanity defense, while nonsignificant trends suggest that labeling psychopathy as a brain disease may ameliorate the stigma surrounding the disorder.