Also known as: M'Naghten test · M'Naghten rule · M'Naghten rules · McNaughton test · McNaghten test
Written by attorneys — see sources below.
A common-law test for legal insanity under which a defendant is entitled to acquittal if a disease of the mind caused a defect of reason such that the defendant lacked the capacity either to know the nature and quality of the act or to know that the act was wrong.
Meredith Maxwell suffered from schizophrenia that produced an overpowering urge to set fires. She deliberately ignited a warehouse while fully aware she was burning property and that the law forbade it. Because she retained the capacity to understand the nature of her act and its legal wrongfulness, the traditional M'Naghten test provided no defense even though her illness destroyed her ability to refrain.
Mohan Malhotra believed his neighbor was a government hologram rather than a person. He fired a rifle at the neighbor while knowing he was pulling a trigger but convinced the target could not be harmed. The delusion prevented him from grasping the physical nature of shooting a human being, satisfying the M'Naghten cognitive prong and supporting acquittal.
Monte Durham was convicted of housebreaking by the District Court of the District of Columbia sitting without a jury. The prosecution proceeded on a charge arising from an incident on July 13, 1951, in which Durham was found in a house. Durham's history included discharge from the Navy in 1945 at age seventeen following a psychiatric examination revealing a profound personality disorder rendering him unfit for service. In 1947 he pleaded guilty to violating the National Motor Theft Act and was placed on probation for one to three years. In January 1948, as a result of a conviction in the District of Columbia Municipal Court for passing bad checks, the District Court revoked his probation and he commenced service of his Motor Theft sentence. His conduct within the first few days in jail led to a lunacy inquiry in the Municipal Court where a jury found him to be of unsound mind. Upon commitment to St. Elizabeths he was diagnosed as suffering from 'psychosis with psychopathic personality.' He experienced multiple discharges and readmissions to St. Elizabeths between 1949 and 1951, including a conditional release in June 1950 that he violated, and a further lunacy finding in 1951. Following the July 1951 housebreaking, Durham was indicted in October 1951 and adjudged of unsound mind based on psychiatrists' affidavits diagnosing psychosis with psychopathic personality. He underwent subshock insulin therapy during a six-month commitment ending in February 1953, after which Dr. Silk certified him mentally competent to stand trial and able to assist counsel. At the ensuing trial, the prosecutor expressed a plan to allow Durham to raise an insanity defense on this charge. The court accepted waivers of jury trial and additional competency proceedings despite Durham's expressed desire for further hospitalization. Testimony included that of Durham's mother regarding his post-May 1951 behavior and a psychiatrist who examined him in September 1951 and opined on his mental condition around the time of the offense. The trial court found the defense of insanity not established under the prevailing standards. The appeal reached the United States Court of Appeals for the District of Columbia Circuit.
View caseNo. The traditional test is strictly cognitive. A defendant who knows the nature and quality of the act and knows it is wrong remains criminally responsible even if mental illness made the conduct feel irresistible.
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The defendant must lack the capacity to recognize that society and the criminal law regard the conduct as wrongful. A sincere personal belief that the act is morally justified does not suffice if the defendant still understands society's contrary judgment.
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A delusion satisfies the test when it prevents the defendant from understanding that the victim is a real human being or that the physical act is causing harm to a person. In such cases the defendant does not comprehend the nature and quality of the conduct.
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No. The test requires proof that the disease caused a defect of reason at the precise time of the offense that eliminated the defendant's capacity to know the nature and quality of the act or its wrongfulness. A past diagnosis alone is insufficient.
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…64-68, 109-47 (1933); Leland v. State of Oregon , 1952, 343 U.S. 790, 800, 72 S.Ct. 1002, 96 L.Ed. 1302. 'In five States the M'Naghten Rules have been in substance re-enacted by statute.' Royal Commission Report 409; see, e.g., Sec. 1120 of the New York Penal Law (McKinney Consol. Laws, c.40) which provides that a person is not…