Several recent studies have examined the effects of mental health and neuroscientific evidence on attitudes toward criminal defendants, suggesting that these factors may influence juror decision‐making in meaningful ways. Few studies to date have manipulated both of these variables while also considering theoretically important individual difference variables (e.g., political orientation). Using a criminal case simulation, this study manipulated the presence of evidence concerning mental disorders (psychopathy and schizophrenia) and increasing levels of neuroscientific detail regarding a defendant's brain injury, and examined verdicts and sentencing recommendations in over 400 persons attending jury duty. Main effects were detected for mental health testimony and political orientation, although interactions were noted as well. More negative reactions to defendants labeled as psychopaths were relatively consistent, whereas participants who identified as liberal generally were less punitive towards a defendant identified as schizophrenic than were more conservative jurors. Consistent with other recent research, juror perceptions of the defendant's level of psychopathic traits (independent of the effects of the experimental manipulations) predicted guilty verdicts and longer sentencing recommendations. Copyright © 2016 John Wiley & Sons, Ltd.