​KembaraXtra – Legal Terms – M’Naghten Rules


The M’Naghten Rules are legal principles governing the defence of insanity in criminal law.


They originated from the case of Daniel M’Naghten and establish the test for determining whether a defendant should be considered legally insane at the time of committing an offence.


Under the rules, a defendant may avoid criminal liability if, because of a defect of reason caused by disease of the mind, he did not understand the nature and quality of the act or did not know that it was wrong.


The rules remain central to the law of insanity in many common-law jurisdictions.


They focus on cognitive understanding rather than emotional or moral incapacity.