Daniel McNaughton - A 19th Century Botched Assassination Attempt Changes U.K. Law

  In 19th Century England, it had been accepted in law that sometimes a perpetrator knew what they were doing or were responsible for their actions and sometimes they weren't. 

 On the 20th of January 1843, however, a Scottish woodworker and out of work actor Daniel McNaughton took a break from passive activism and set out to assassinate Tory prime minister Robert Peel. Wandering around the houses of parliament, with murderous intent, he approached a man whom he thought was Peel. In fact, it was Peel's private secretary Mr Drummond. He drew his pistol and fired a shot at point-blank range into his back. Before he could fire the next shot he was apprehended by a passing police officer. Mr Drummond was rushed to hospital but died a few days later, which meant that McNaughton found himself in the dock charged with murder.

 The defence called nine witnesses to the stand during the trial, who all testified that McNaughton had been acting out of character and suspiciously on the weeks leading up to the tragic event. Some even went on to say that he was suffering from paranoid delusions and hallucinations. He had proclaimed to them all that the entire Tory party were following him everywhere and had whispered to others in his presence that they needed to eliminate him. Despite this, the prosecution argued that he was capable of knowing right from wrong still, despite claiming to have some sinister conspiratory motive for striking first. The jury found him not guilty on the grounds of insanity, and he was sentenced to spend the rest of his life in an insane asylum. 

 McNaughton's acquittal caused a huge outcry over the country, and even from Queen Victoria herself who had been the victim of several assassination attempts.

 Unable to ignore the large public unrest a panel of judges were asked to answer a series of questions pertaining to this trial. The responses were correlated to what is known now as "The McNaughton Rule", which is given to jury members before an insanity case is tried. It says that the defendant will be assumed to be sane until a plea of insanity is accepted then certain medical tests and experts must prove that the defendant is insane and was not compos mentis at the time of the crime.