The present study investigated the impact of diagnostic labels and traits, age, and gender of the defendant on various mock juror decisions. Undergraduate students and members of the community (N=247) read a simulated trial transcript involving a case of aggravated assault. The transcript differed in terms of diagnosis (psychopathy vs. antisocial personality disorder (APD)/conduct disorder (CD) vs. no diagnosis), age (15 vs. 30), and gender (male vs. female) of the defendant. The effects of these variables on decisions regarding credibility, verdict choice, risk of future violence and recidivism, and treatment amenability were investigated. Results indicated that psychopathic defendants were rated as being less credible than defendants in the other diagnostic conditions. Defendants described as psychopaths and as having APD/CD were also more likely to be found guilty and were more likely to receive higher ratings of risk for future violence/recidivism regardless of their age and gender. There were no significant main effects or interactions concerning the age and gender variables. Implications for the use of psychopathy evidence within the Criminal Justice System are discussed.