M'Naghten rules

Daniel McNaughton c 1856

M'Naghten Rules

The M'Naghten Rules, also known as the M'Naghten test, are a set of legal guidelines for determining criminal responsibility in cases of insanity. These rules were established in 1843 by the British courts following the acquittal of Daniel M'Naghten, who had been charged with the attempted assassination of the British Prime Minister, Sir Robert Peel.

According to the M'Naghten Rules, a person can be found not guilty by reason of insanity if, at the time of the crime, they were suffering from a mental disorder that rendered them unable to understand the nature and quality of their actions, or to distinguish right from wrong. The burden of proof lies with the defense to establish the presence of a mental disorder that meets these criteria.

The M'Naghten Rules have been influential in shaping the legal standards for insanity defenses in many common law jurisdictions, including the United States and various Commonwealth countries. However, they have also been subject to criticism for their narrow focus on cognitive impairment and their failure to account for other factors that may affect criminal responsibility, such as volitional control.

In practice, the application of the M'Naghten Rules can be complex and controversial, as courts must weigh psychiatric evidence and legal principles to determine whether a defendant meets the criteria for insanity. The rules continue to be a subject of debate among legal scholars, mental health professionals, and policymakers seeking to balance the interests of justice, public safety, and the rights of individuals with mental illness.