trial of Daniel McNaughton

The trial of Daniel McNaughton concerned his mental state when he attempted to assassinate Prime Minister Robert Peel in 1843. McNaughton believed he was acting to prevent harm from the Prime Minister, whom he mistakenly thought was part of a conspiracy against him. The case raised important questions about criminal responsibility and mental illness, leading to the famous "M'Naghten Rules." These rules establish that a person is not guilty if, at the time of the crime, they were suffering from such a defect of reason from mental illness that they did not understand the nature of their act or know it was wrong.