Everyone has probably at least heard of the insanity defense in criminal proceedings, but I believe many may not know the history behind it or the practical use of it. Quick disclosure, I am not a lawyer. My background is in psychology, but I did find what I believe to be information from reputable sources.
The insanity defense is a legal defense that a person is not responsible for their crimes because they were not of sound mind when they committed said crimes. However, the insanity defense is not the same as diminished capacity. While they are similar, there are some key differences. Insanity is essentially saying they are not guilty of their crime whereas diminished capacity is saying they committed a lesser crime (e.g. manslaughter as opposed to murder). Diminished capacity can be used to influence the intent behind a crime like premeditation.
Tests for legal insanity have changed several times over the years. It began as the M'Naghten rule, which could be applied by the jury after hearing testimony from medical professionals. This created an assumption of sanity unless the defense proved, "at the time of committing the act, the accused was laboring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing or, if he did know it, that he did not know what he was doing was wrong." Interestingly, this is the still the standard in half of the United States, even though it was established in 1843.
The Irresistible Impulse test of insanity addresses those who know what they did was wrong, but they could not stop themselves. Unlike the M'Naghten rule, this is far less supported scientifically.
The Durham Rule aka The "Product" Test says that "that an accused is not criminally responsible if his unlawful act was the product of mental disease or mental defect." This is essentially an updated version of the M'Naghten rule because an appellate judge believed the M'Naghten rule to be based on outdated scientific evidence. While this started as a good thing, problems arose. The test was viewed as conclusory and deprived the jury of their decision-making role in determining criminal insanity. It was also viewed as too inclusive because there was no concrete definition of "mental disease or mental defect."
In 1972, a panel of legal experts tried to modernize the insanity defense. They developed a new rule known as the Model Penal Code, and it says "that a defendant is not responsible for criminal conduct where (s)he, as a result of mental disease or defect, did not possess a "substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law."" This allows the opportunity for a broader definition of wrongfulness and criminality. Additionally, it says that criminal liability cannot apply if a person was unable to conform to the law.
Lastly, the Criminal Crime Control Act was passed in 1984 and required clear and convincing evidence in order for a defendant to use the insanity defense. This also set up the "knowing right from wrong" standard that is commonly used today.
Because of how this has been portrayed in popular culture, there are several common misconceptions about the insanity defense. The first being that insanity is a psychiatric term when it's really a legal term. It's purely about if that person should be considered responsible for the crime and does not comment on the state of their mental illness/disorder. Another common misconception is that the insanity defense evaluates a person's current mental state, but it really evaluates their mental state at the time the crime was committed. A third misconception is the rate at which this defense is used. It's really only used in about 1% of cases and is only successful about 1/4 of the time. A fourth misconception is that people who successfully use the insanity defense go free quickly when in reality, they usually spend about three years in a psychiatric facility, often spending more time than their criminal sentence would have been. In fact, most states have requirements for treatment and institutionalization.
Sources:
Psychology: From Inquiry to Understanding (4th edition) by Lilienfeld, Lynn, and Namy, Chapter 15
Legal Information Institute at Cornell Law School: https://www.law.cornell.edu/wex/insanity_defense
Comments