MNaghten Rules Answers of the House of Lords relating to questions where the accused, acting under insatie delusion, killed the secretary of Sir Robert Peel and was found not guilty on the ground of insanity. The Rules remain legal criteria when insanity is pleaded as a defence. They state: (1) A person is presumed sane until the contrary is proved. (2) To establish a defence on the ground of insanity, it must be clearly proved that at the time of committing the offence, the accused was labouring under such, a defect of reason, from disease of the mind, as not to know the nature and quality of his act, or, if he did know it, that he did not know what he was doing was wrong. If the accused was conscious that the act was one he ought not to do and if that act was at the time contrary to law of the land, he is punishable. (3) Where a person under an insane delusion as to existing facts commits an offence in consequence thereof, and making the assumption that he labours under such partial delusion only, and is not in other respects insane, he is considered in the same situation as to responsibility as if the facts with respect to which the delusion exists were real.