John M'Naghten

John M'Naghten was a Scottish man whose case in 1843 led to the establishment of a legal standard for insanity in criminal law. After killing a government official, he was judged to be insane and unable to understand the nature of his actions or distinguish right from wrong at the time of the crime. The "M'Naghten Rule," stemming from this case, is now used in many jurisdictions to assess whether a defendant was mentally ill and could be held responsible for their actions during the commission of a crime. It emphasizes the importance of mental state in legal accountability.