Insanity defence

Established in M'Naghten
D must suffer from a 
- defect of reason 
- caused by a disease of the mind 
- D doesnt know the nature and quality of his act or does not realise what he is doing is wrong. 

1) defect of reason 
Powers of reasoning must be impaired 
2) Disease of the mind 
Any physical or mental disease which affects the mind - R V Kemp 
R V Sullivan - doesnt have to be permanent, just present at time of offence. 
Burgess - includes sleepwalking 
Quick + Hennessy - diabetic attacks from an internal factor 
3) Not knowing nature or quality of act and not know act was legally wrong
- 2 ways this is done
- being unconscious 
-conscious but not aware of what he is doing due to disease of mind 
-legally wrong not morally wrong - R V Windle