What is M'Naghten Rule?

The M'Naghten rule is a legal concept that aims to determine whether a defendant is legally insane at the time of committing a crime.

This test is applied in some common law jurisdictions, including England, Wales, and some US states, to assess a defendant's mental state during the criminal act.

It was established in the 1843 case of R v M'Naghten, where the defendant was found not guilty by reason of insanity in the murder of the Prime Minister's private secretary.

According to the M'Naghten rule, a defendant is considered legally insane if, at the time of the offense, they were laboring under such a defect of reason that they didn't comprehend the nature and quality of the act they were committing, or if they did, they did not realize that what they were doing was wrong.

For the rule to apply, the defendant must have had a mental illness or defect that impaired their ability to understand the nature and consequences of their actions, and their ability to differentiate between right and wrong.

Critics argue that the M'Naghten rule is too narrow and doesn't take into account current scientific and medical knowledge about mental illness. Some jurisdictions have implemented alternative tests such as the irresistible impulse test, which offers a more extensive consideration of mental illness and the defendant's capability to control their behavior at the time of the offense.

These alternative tests have more room for interpretation, making them a more comprehensive assessment tool for legal professionals.