The Insanity Defense: Historical Precedent and Modern Application

Abstract

Mental health professionals need a basic understanding of the insanity defense. This article provides an overview of the historical origins of the defense and current application. The word “insanity” has a special meaning in the judicial system, one that is different than that used by medical professionals. A successful insanity defense allows a defendant to be found “not guilty by reason of insanity.” Although this verdict is an acquittal, it almost always leads to commitment to a psychiatric facility. Courts give considerable weight to the opinions of psychiatric experts when assessing an insanity plea. To provide such an opinion, a psychiatrist must understand their jurisdiction's insanity standard, review the facts of the case, and perform detailed interviews. Using this information, a psychiatrist can offer an opinion on a defendant's state of mind at the time of the crime. [ Psychiatr Ann. 2018;48(2):95–101.]