Juror’s Take on the Insanity Defense

The insanity defense can be very controversial and often receives a lot of media attention when used in criminal trials. The reason for the controversy is because by using the insanity defense, the criminal defendant is admitting to the action but declares a lack of culpable mind due to mental illness. Thus, the assertion is that the defendant acted with the requisite actus reus but not the requisite mens rea to be convicted of the crime. The idea of the defense in general is conflicting because the defendant admitted to committing the criminal act. However, the act was done alleged to be done without the defendant understanding the action was wrong.

The law surrounding the insanity defense has changed numerous times throughout the years resulting in several standards. The change in standard is relevant because standards effects how the jury is instructed. The evolution of the insanity defense has allowed researchers to study how each standard has been perceived by jurors. The key research question being whether the change in standard influenced jury decision making. The answer, surprisingly, is not really. The studies show that jury decision making has not been substantially affected by the change in the insanity defense standards. Even more shocking, the control experiments, that is jurors who were given no instructions compared to jurors who were given instructions, exposed that those who were given no instructions did not seem to significantly differ in their decisions. That is, the jury still comes to the same conclusion regardless of instruction or lack thereof. 

Scholars reason that this result occurs not because jurors do not consider the instructions, but because jurors will always interpret cases of insanity based on their own understanding of mental illness and the insanity defense. Most jurors have a commonsense understanding of mental illness that they employ when determining whether the defense is valid or not. Thus, it is important to assertion what that common understanding may be.

Professor Michael Perlin identified eight myths the public has about the insanity defense. One, the belief that the insanity defense is overused. Two, defendants who plead insanity are usually faking. Three, the insanity defense is used almost exclusively in cases that involve violent crimes. Four, pleading not guilty by reason of insanity is a strategy used by criminal defense attorneys to get their clients acquitted. Five, there is no risk to the defendant who pleads insanity. Six, trials involving a not guilty by reason of insanity defense almost always feature battles of the experts. Seven, not guilty by reason of insanity acquit-tees spend much less time in custody than do defendants convicted of the same offense. And lastly eight, not guilty by reason of insanity acquittees are quickly released from custody. None of these myths are true and each display the misguided understanding of everyday individuals.

Attorneys should understand the weight the jurors own understanding has on cases in which the insanity defense is used. Voir dire during these cases should focus on determining what understanding the potential juror will bring to deliberations.