What is the M'Naughten Rule? How Fid this rule come into existence?

It's actually is for criminology but it's not on the list

The M'Naughten Rule is a set of instructions that juries are supposed to use to determine whether or not a defendant is criminally insane.

The base assumption with the rule is that all defendants are sane until proven otherwise.

The test comes out of a trial for a man who shot the Prime Minister's secretary.