Understanding Insanity Defense

Insanity or mental disorder defense is used during criminal trials to plead innocence for the crime committed. The defendant must prove to the court that he was not aware of committing the crime, that during the time he did not know what he was doing.

Understanding insanity defense is important to know how it works. Insanity also known as a mental handicap or psychiatric disorder had been used for longest time to defend a person who is not in his proper mind when the criminal act happened.

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There are two kinds of insanity:

•    Cognitive insanity – Using psychiatric test results, the defendant is proven mentally incapacitated during the act of crime. It is allowed by many states to be used as defense in court proceedings.
•    Volitional insanity – It is an irresistible impulse. The defendant knows that what he is doing is wrong, but due to extreme emotions, he loses control of himself and commits the crime. It usually happens during crimes of vengeance or vendetta. Only a few states permit the use of volitional insanity as court defense.

It helps that in understanding insanity defense you need to know its history. It was first used in later part of the 13th century during a court prosecution where the defendant used “complete madness” plea to prove innocence. In 1581, an English treatise stated that “if a madman, a natural fool or a lunatic” committed a crime of killing someone in the throes of his madness, he is not held accountable. During 18th century, British courts used “wild beast” test to prove that the defendant was totally unaware of what he has done. If the test resulted showed that the person had little or no comprehension like a wild beast, brute or infant during the incident, there would be no conviction.

As time evolves, the term lunatic, wild beast or madness are eliminated and replaced with insanity. The legal basis to use insanity in court is codified in British law in the middle of 19th century through M’Naughten Rule. It was used in different courts worldwide and by the majority of states in the United States.

There are various tests used by courts to assess the degree of insanity. It is important in understanding insanity defense to know if the person is totally or partially insane. Some of these tests are:

•    M’Naughten Rule – This test will prove that the defendant has no understanding or comprehension of what he did or why he did it due to mental illness.
•    Durham Rule – Test shows that regardless of any diagnosis, the mental illness of the defendant resulted in a crime.
•    Irresistible Impulse Test – This test shows that because of cognitive impairment, the defendant has no control over his impulses which lead to criminal acts.
•    Model Penal Code Test – It is the test to prove legal insanity. The result will prove that the defendant who is diagnosed with mental defect is unaware the criminal liability of what he has done.

Understanding insanity defense using the results of these tests is important in giving proper judgment. Defendants who are found not guilty due to insanity are given psychiatric treatment in mental institutions. Those who are found guilty, but suffering from temporary insanity are also confined in the institution until such time that they are no longer threats to society.