Daniel McNaughton

Daniel McNaughton was a Scottish man who, in 1843, attempted to assassinate British Prime Minister Sir Robert Peel but mistakenly killed an aide instead. McNaughton was found not guilty by reason of insanity, leading to a legal landmark. His case established the "McNaughton Rule," which defines the legal standard for insanity: a defendant may be excused from criminal responsibility if, at the time of the crime, they were unable to understand the nature of their act or distinguish right from wrong due to a severe mental illness. This principle influences how courts assess mental health in criminal cases today.