The Insanity Defense

Abstract

Chapter 8 addresses the insanity defense, its lengthy and controversial history, its basic threads and iterations, its evolution over time, the current tests employed, and the lack of consensus regarding what the relevant standard should be. This chapter also describes the rationale for and opposition to the defense—although most seem to agree that at least under some circumstances a defendant’s mental status at the time of the crime is a factor that should be relevant during subsequent criminal proceedings—and various widely-held myths regarding its prevalence, use, and impact. The chapter begins with descriptions of a series of notorious cases where an insanity defense was raised or widely thought to have been raised. For better or for worse, these cases have generally shaped the public’s perception of this defense. The chapter ends with an account of the single U.S. Supreme Court ruling that directly addressed whether the insanity tests currently employed are subject to constitutional scrutiny.