法律英语：35 Insanity Defense

by Michael W. Flynn

 

First, a disclaimer: Although I am an attorney, the legal information in this podcast is not intended to be a substitute for seeking personalized legal advice from an attorney licensed 1 to practice in your jurisdiction 2. Further, I do not intend to create an attorney-client relationship with any listener.   

 

Today I will discuss an aspect of the defense 3 of insanity 4 to a crime. Tracy from East Melbourne, Australia wrote:

 

Hi, Legal Lad. I'm confused about the insanity defense. If it's obvious that a person committed a crime (say, murder), but is also obviously mentally incapable 5 of understanding his/her actions, why isn't that person GUILTY by reason of insanity? Why is it always NOT GUILTY by reason of insanity?

 

This question really jumped off the page for me because it does seem odd on a practical level that someone who kills another human being could be “not guilty” simply because he is nuts.

 

Almost all crimes require both an actus reus, and a mens rea. Actus reus refers to the criminal act, while mens rea refers to the “guilty mind.” In common law countries such as the United States, the United Kingdom, and Australia, the test of criminal liability is usually expressed in the Latin phrase, “actus non facit reum nisi mens sit rea,” which means that “the act does not make a person guilty unless the mind is also guilty.”

 

In the context of murder, the government must first prove the actus reus. That is, the government must prove, beyond a reasonable doubt, that the defendant 6 actually killed somebody.

 

The government must also prove that the defendant intended mentally to commit the illegal act. There are varying degrees of intent for homicide that result in varying charges and punishment. For example, consider the defendant who creates an elaborate plot to murder his wife with arsenic 7 over the course of several months. Now consider the defendant who, while working on a construction site, accidentally drops a hammer that falls 40 stories, killing 8 his wife who happens to be passing underneath 9. In both situations, there is a dead wife. The actus reus is the same because both men caused the death of their wives. But, the law treats the two defendants 10 differently because the men had different mental states. One maliciously 12 intended to kill his wife and planned for it months in advance. The other had no such previous malicious 11 intent. So, the devious 13 poisoner might be convicted of first degree murder, while the clumsy construction worker might be convicted of involuntary manslaughter, which carries a much lighter 14 sentence.

 

With regard to insanity, the insanity defense effectively negates 15 the mens rea of the murder. If a person is incapable of understanding the consequences of his actions, the government cannot prove that he intended for the death to occur. In order to obtain a conviction, the government must prove all elements of its case beyond a reasonable doubt, including the requisite 16 mens rea. If the government fails to prove all its elements, then the defendant is “not guilty.”

 

But please understand that, when a defendant is found “Not guilty by reason of insanity,” the defendant is not free to go. The defendant will be confined to a mental health facility. Also, the insanity defense rarely works in the United States because it is so difficult to prove that a person could not understand the consequences of his actions.

 

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