07/05/21
DEFENCE OF INSANITY
Insanity is a defence to all crimes
Common law defence - verdict comes from the Trial of Lunatics Act
If found “not guilty by reason of insanity”, defendant may get a hospital and
treatment order, a supervision order or an absolute discharge.
R v M’naghten - 3 stage test
1) Defect of reason
2) The defect must be caused by a disease of the mind
3) The defect must be such that the defendant did not know what they were
doing or, if they did know, they did not know the act was wrong (legally
wrong)
DEFECT OF REASON - “inability to use the powers if reasoning” (R v
Clarke). Not enough to just be absent minded, there must be a full
deprivation of powers of reasoning.
MUST BE CAUSED BY A DISEASE OF THE MIND
(Bratty v AG for NI) mental faculties of reason, memory and
understandings. Must be an internal cause of harm.
Arteriosclerosis, medically proven temporary loss of consciousness (R v
Kemp)
Epilepsy - recognised condition as a disease of the mind (Bratty) (R v
Sullivan)
Sleepwalking - (R v Burgess)
Hyperglycaemia arising from diabetes - (R v Hennessey) failure to take
insulin
DEFENDANT DID NOT KNOW WHAT THEY WERE DOING, OR THEY DID NOT
KNOW IT WAS WRONG
R v Windle - he knew what he did was wrong
R v Bell -knew his actions were wrong, not even messages from God are
enough
DEFENCE OF INSANITY
Insanity is a defence to all crimes
Common law defence - verdict comes from the Trial of Lunatics Act
If found “not guilty by reason of insanity”, defendant may get a hospital and
treatment order, a supervision order or an absolute discharge.
R v M’naghten - 3 stage test
1) Defect of reason
2) The defect must be caused by a disease of the mind
3) The defect must be such that the defendant did not know what they were
doing or, if they did know, they did not know the act was wrong (legally
wrong)
DEFECT OF REASON - “inability to use the powers if reasoning” (R v
Clarke). Not enough to just be absent minded, there must be a full
deprivation of powers of reasoning.
MUST BE CAUSED BY A DISEASE OF THE MIND
(Bratty v AG for NI) mental faculties of reason, memory and
understandings. Must be an internal cause of harm.
Arteriosclerosis, medically proven temporary loss of consciousness (R v
Kemp)
Epilepsy - recognised condition as a disease of the mind (Bratty) (R v
Sullivan)
Sleepwalking - (R v Burgess)
Hyperglycaemia arising from diabetes - (R v Hennessey) failure to take
insulin
DEFENDANT DID NOT KNOW WHAT THEY WERE DOING, OR THEY DID NOT
KNOW IT WAS WRONG
R v Windle - he knew what he did was wrong
R v Bell -knew his actions were wrong, not even messages from God are
enough
