Juror impartiality is necessary for a fair and just legal system, but is true juror impartiality

realistic? The current study investigated the role of implicit and explicit social-cognitive biases in jurors’ conceptualizations of insanity, and the influence of those biases in juror verdict decisions. It was hypothesized that by analyzing the role of implicit and explicit biases in insanity defense cases, jurors’ attitudes towards those with mental illnesses and attitudes towards the insanity defense would influence jurors’ final verdict decisions. Two hundred and two participants completed an online survey which included a trial vignette incorporating an insanity defense (adapted from Maeder et al., 2016), the Insanity Defense Attitude Scale (Skeem, Louden, & Evans, 2004), Community Attitudes Towards the Mentally Ill Scale (Taylor & Dear, 1981), and an Implicit Association Test (Greenwald et al., 1998). While implicit associations concerning mental illness and dangerousness were significantly related to mock jurors’ verdicts, they no longer were when explicit insanity defense attitudes were added to a more complex model including all measured attitudes and biases. Insanity defense attitudes were significantly related to jurors’ verdicts over and above attitudes about the mentally ill and implicit biases concerning the mentally ill. The potentially biasing impact of jurors’ insanity defense attitudes and the impact of implicit associations about the mentally ill in legal judgments are discussed.