What is the M’Naghten Rule – the Basis of Insanity Defenses?

29August
2019

The M’Naghten Rule is the basis of insanity defenses in the United Kingdom and the United States. It was established by the British House of Lords in the mid-19th Century.

The rule is a test of whether the person accused of a crime was sane when the act was committed and criminally responsible for what happened. The rule is named after Daniel M’Naghten, a man who tried to kill the British Prime Minister Sir Robert Peel. M’Naghten apparently believed that Peel wanted to kill him. He tried to assassinate the Prime Minister but instead shot his private secretary, Edward Drummond dead in 1843.

How the M'Naghten Rule developed in the 19th Century led to the insanity defense
The M’Naghten Rules forms the basis of the insanity defense

Medical experts were brought in for M’Naghten’s murder trial. They testified that he was psychotic. M’Naghten wad found not guilty by reason of insanity. The verdict caused an outcry from the public who had never heard of an insanity defense.

The House of Lords ordered the courts to draw up a strict definition of criminal insanity that could be used in future criminal trials. The result was the M’Naghten Rule. The justices ruled that insanity was a defense only when if the accused had a defect of reason at the time the crime was committed. The defendant should not have known about the nature of his or her actions and been too deranged to realize they were wrong.

The M’Naghten Rule was first applied by the courts in the United States in the 19th Century, just a few years after the British ruling. The Journal of the American Academy of Psychiatry and Law reported how in 1846, New York State tried William Freeman who was accused of killing several members of the Van Nest family near Auburn, New York. Freeman demonstrated psychotic behavior. He was obsessed with horse theft and false imprisonment. William Seward, his defense lawyer, wanted an insanity verdict and used the M’Naghten Rule argument. Although Freeman was clearly impaired, a jury found him competent to stand trial.

A jury found Freeman guilty of the killings and a judge sentenced him to death. Seward filed a Writ of Error. The New York State Supreme Court reversed Freeman’s conviction and death sentence. The court said the M’Naghten Rule would be the standard in New York.

The M’Naghten rule underpins Arizona’s guilty except insane (GEI) defense. It allows the defendant in a case to show evidence of a serious “mental disease or defect.” Specific conditions can qualify for GEI. The effects of withdrawal from drugs and alcohol, impulse control, or psychosexual disorders do not meet the definition of guilty except insane. This is a hard defense to prove. The defendant must suffer from a condition that’s so serious, he or she was unaware that the criminal act was wrong.

If you or a family member has a mental disorder and is facing charges, our law firm can help you. Attorney Bernardo Garcia has assisted clients in these cases for decades. Please call him at (602) 340-1999.

Posted in Arizona Laws, Mental Health, Mental Health Defenses | Tagged |