20Defence of mental impairment

20 Defence of mental impairment (1) The defence of mental impairment is established for a person charged with an offence if, at the time of engaging in conduct constituting the offence, the person was suffering from a mental impairment that had the effect that— (a) he or she did not know the nature and quality of the conduct; or (b) he or she did not know that the conduct was wrong (that is, he or she could not reason with a moderate degree of sense and composure about whether the conduct, as perceived by reasonable people, was wrong). (2) If the defence of mental impairment is established, the person must be found not guilty because of mental impairment.