Insanity & Criminal Behavior

Kaitlin Smith

“Madness in our age has become some sort of lost truth (Foucault, 1967).”

On June 20, 2001, a Texas resident and young mother committed the unthinkable crime.  She took the lives of her five innocent children by drowning them in a bathtub (

After America was shocked with the news of this heinous crime, many hoped justice would be served.  Instead of life in prison or the death penalty, Andrea Yates was ruled Not Guilty By Reason of Insanity and now resides in a state mental hospital (

Many feel that the Not Guilty by Reason of Insanity plea is a loophole in the law that allows culprits to escape responsibility for their actions (Ennis, 1982).

Ironically, while the insanity plea is one of the most notorious and controversial defense approaches, it is rarely used.  There are currently only 3,500 individuals in the United States that fall under the not guilty by reason of insanity plea (Hathaway, 2009).

The idea of insanity is a complex and difficult term to define, an issue which only adds to the disputable nature of the topic.  Often when people hear the word, they think of a deranged and deluded individual; one with no concept of reality.  The definition, however, quickly transformed from a medical term into a legal one.  The Concise Medical Dictionary declares that insanity refers to, “A degree of mental illness such that the affected individual is not responsible for his actions or is not capable of entering in a legal contract” (Tighe).  The definition for criminal insanity is fairly similar: “The individual’s mental make-up at the time of the offending act was such that, with respect to the criminality of his conduct, he substantially lacked capability to act rationally” (Hathaway, 2009).

The theory behind the defense is that a person who is insane lacks the intent required to execute a criminal act because the person either does not know that the act is wrong or cannot control his or her actions even when the person understands that the act is wrong. The situations in which insanity can be used to excuse criminal responsibility are difficult to characterize.  While many states in the U.S. use many different terms to define insanity, a commonly used rule of thumb comes from a case that took place in England known as the M’ Naghten Rule which states that “a defendant is legally insane only if, as a result of a defect of reason from a disease of the mind, at the time of the act he did not know either the nature and quality of the act or that the act was wrong” (Emanuel, 1989).

It is also argued that insanity is inconsistent and while the defendant may have been in a psychotic state during the time the crime was committed, he or she may not be during the trial.  While the jurors draw inferences about the defendant’s mental state during the time of the crime based on his or her behavior during the trial, improper verdicts could possibly result (Pickel, 1998).

Emanuel, Anne S.  (1989).  Guilty but Mentally Ill Verdicts and the Death Penalty: an Eighth Amendment Analysis.  North Carolina Law Review.

Ennis, B. (1982). Straight Talk About the Insanity Defense. Nation, 235(3), 70-72. Retrieved from Legal Collection database.

Foucault, Michael.  (1967). Madness and Civilization: a History of Insanity in the Age of Reason.  United Kingdom: Tavistock Publications.

Hathaway, M. (2009). The Moral Significance of the Insanity Defence. Journal of Criminal Law, 73(4), 310-317. doi:10.1350/jcla.2009.73.4.581.

McNamara, Melissa.  July, 2006.  Andrea Yates Found Not Guilty By Reason of Insanity; Will Be Committed to State Hospital. Retrieved 26, November 2010, from

Pickel, Kerri.  (1998). The effects of motive information and crime usualness on jurors’ judgments in an insanity case. Law and Human Behavior, 22, 571-584. doi: 10.1023/A:1025791530881

Tighe, J. (2005). What’s in a name?—a brief foray into the history of insanity in England and the United States. J Am Acad Psychiatry Law 33:252- 8, 2005

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