M’Naghten (defendant) mistakenly shot Edward Drummond, secretary to the prime minister, believing he was the prime minister, Sir Robert Peel. Upon his arrest, M’Naghten told police that he had come to London to murder Peel because “[t]he tories in my city follow and persecute me wherever I go, and have entirely destroyed my piece of mind. [T]hey do everything in their power to harass and persecute me; in fact they wish to murder me.” At trial, defense counsel introduced extensive expert and lay evidence to show that M’Naghten was obsessed with delusions and suffered from acute insanity. Consequently, the trial judge instructed the jury that if M’Naghten was not “sensible” or “in a sound state of mind” at the time of the crime, then he should not be found guilty. The jury returned a verdict of “not guilty, on the ground of insanity.” Thereafter, members of the English judiciary convened to discuss the theory of insanity as a defense to a criminal charge.