M Naghten Case Analysis

The way we determine if someone is mentally insane began with the M 'Naghten case (1843) which developed the first test to determine if the defendant is insane. It set the standard that the jury has to decide if the defendant is insane only after hearing a medical testimony from the prosecution and defense experts. The rule created the presumption of sanity, unless the defense proved "at the time of committing the act, the accused was laboring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing or, if he did know it, that he did not know what he was doing was wrong" (Francone, 2016). They will be deemed insane only if they were found incapable of knowing what they were doing

This emphasized the need for scientific psychological evaluations and evidence to be presented in the court which ultimately left it up to the jury to decide if the defendant was in fact insane. Then they developed the Model Penal Code (1972) which created the idea that the defendant cannot be responsible for a crime when it is a result of their mental state. They did not possess a "substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law" (Francone, 2016). Lastly in 1984, Congress passed the Comprehensive Crime Control Act which requires the defendant to prove that by "clear and convincing evidence," that "at the time of the commission of the acts constituting the offense, the defendant, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts" (Francone, 2016). This returned the idea of knowing right from wrong as the standard. Currently, all states use one or a combination of these tests to determine insanity in criminal court