Insanity Defense Consequences

The insanity defense is rarely used, even more rarely successful, and persistently poorly understood. A half century's worth of research indicates that potential jurors (i.e., members of the general public) harbor misconceptions about the insanity defense, including that defendants found not guilty by reason of insanity (NGRI) are essentially allowed to walk out of the courtroom freely, with no further consequences. Inaccurate beliefs like these threaten to influence juror decision making, as retributivist notions of justice (e.g., a person who does wrong must be punished) and safety concerns (e.g., fear that dangerous defendants will be allowed back into the community) may dissuade jurors from reaching an NGRI verdict, even if the facts of the case demand such a conclusion. For jurors to fulfill their roles as impartial triers of fact, it is critical that they operate with accurate information about the insanity defense. This study examined one potential means of achieving this goal: using jury instructions to inform jurors of the consequences of an NGRI verdict. It utilized a 3-group design to test whether receiving information on NGRI verdict consequences would: (1) decrease the likelihood of jurors reaching a guilty verdict, (2) result in a more accurate understanding of the insanity defense, and (3) result in a more favorable attitude towards the insanity defense. Mock jurors were recruited online, provided a fictional case vignette, and asked to reach a verdict. They also completed validated questionnaires to measure their knowledge of and attitude toward the insanity defense. Results for all hypotheses revealed no significant differences across groups. Possible explanations of these results and suggested future research directions are discussed.