General Defences Criminal Law
GENERAL DEFENCES
Insanity, automatism and intoxication they all relate to the issue of whether D had rational
capacity (RC) at the time of the act.
==================================================================================
INSANITY:
Also known as insane automatism
Concerned with the mental condition of the defendant at the time of the offence
Burden is on the defendant, who will argue that he is unfit to plead
General defence – can be used as a defence for any crime (which require mens rea)
Can be used in Crown court and Mag court (Horseferry Rd Magistrates Court exparte 1996)
Defence not available to strict liability offences such as driving with excess alcohol
Burden of proof:
Presumption = every man is presumed to be sane
If D wishes to rely on this defence, they must rebut this presumption
Burden of proof rests with the defence
For the D to prove on a balance of probabilities (insanity is an exception to the general rule that
the burden rests on the prosecution to disprove the defence beyond reasonable doubt)
The Criminal Procedure (Insanity and Unfitness to Plead) Act 1991:
Substituted a new s5 into the Criminal Procedure (Insanity) Act 1964
Now, following a special verdict, the judge may make either:
o A hospital order (with or without a restriction order)
o A supervision order, or
o An order for absolute discharge
Particularly useful where the offence is trivial and/or the defender does not require treatment
The new power does not apply to murder cases – in these cases indefinite hospitalisation is
unavoidable
The 1991 does not tackle the definition of insanity
D may have the defence of insanity available to them
If successfully proven, will lead to a special verdict of ‘not guilty by reason of insanity’ (s1
Criminal Procedure (insanity) Act 1964)
o Until recently, this special verdict obliged the judge to order D to be detained
indefinitely in a mental hospital
The key case of M’Naughten, where the D attempted to assassinate the prime minister due to
his delusions, provides that everyone is “sane unless proven otherwise”
, General Defences Criminal Law
o M’Naughten (1843) 10 C1 & F 200:
Radical and chartist supporter
Wanted to assassinate the prime minister, Robert Peel
Shot his private secretary, believing it to be Peel, in the back
o The rules are not binding as a matter of a strict precedent
o Nevertheless, the rules have been treated as authoritative ever since
o Rules;
Every man is presumed sane
To establish insanity, the D must show, on a balance of probabilities, that at the
time he was suffering from:
A defect of reason
Caused by a disease of the mind
He did not know the nature and quality of his act, or what he was doing
was wrong
Judge: the question whether the D was suffering from a defect of reason caused by a disease of
the mind is a question of law to be determined by the trial judge
Jury: the issue of whether the D knew the nature and quality of the act, or if he did know it,
whether he knew it was wrong, is a question of fact to be determined by the jury
Firstly, the D must suffer from a ‘defect of reason´ which requires an impairment of reasoning
This means being ‘deprived of the power of reasoning,’ rather than just ‘failing to use it’
Short periods of absent-mindedness are not sufficient - Clarke 1972:
o Old woman shoplifted
Can be permanent or temporary if recurrent e.g. Sullivan 1984 (epilepsy), D kicked V whilst
suffering from epileptic fit
In this scenario, D has a defect of reason because…
Secondly, the defect of reason must be due to a ‘disease of mind’
The disease must affect the ‘mind’ rather than the brain in the physical sense
The disease must affect the ordinary mental faculties of “reason, memory and understanding”
(per Devlin J in Kemp 1957)
This can be mental or physical, as in the case of Kemp (hardening of arteries)
o Kemp 1957:
Hardening of arteries
Attacked wife with hammer
Must be caused by an internal factor e.g. hyperglycaemia, as in the case of Hennessy, where D
failed to take insulin. However, in Quick, D took insulin but failed to eat afterwards, resulting in
hypoglycaemia (external factor – automatism)
o Hennessy 1989:
Failed to take insulin
Stole car
o Quick 1973:
GENERAL DEFENCES
Insanity, automatism and intoxication they all relate to the issue of whether D had rational
capacity (RC) at the time of the act.
==================================================================================
INSANITY:
Also known as insane automatism
Concerned with the mental condition of the defendant at the time of the offence
Burden is on the defendant, who will argue that he is unfit to plead
General defence – can be used as a defence for any crime (which require mens rea)
Can be used in Crown court and Mag court (Horseferry Rd Magistrates Court exparte 1996)
Defence not available to strict liability offences such as driving with excess alcohol
Burden of proof:
Presumption = every man is presumed to be sane
If D wishes to rely on this defence, they must rebut this presumption
Burden of proof rests with the defence
For the D to prove on a balance of probabilities (insanity is an exception to the general rule that
the burden rests on the prosecution to disprove the defence beyond reasonable doubt)
The Criminal Procedure (Insanity and Unfitness to Plead) Act 1991:
Substituted a new s5 into the Criminal Procedure (Insanity) Act 1964
Now, following a special verdict, the judge may make either:
o A hospital order (with or without a restriction order)
o A supervision order, or
o An order for absolute discharge
Particularly useful where the offence is trivial and/or the defender does not require treatment
The new power does not apply to murder cases – in these cases indefinite hospitalisation is
unavoidable
The 1991 does not tackle the definition of insanity
D may have the defence of insanity available to them
If successfully proven, will lead to a special verdict of ‘not guilty by reason of insanity’ (s1
Criminal Procedure (insanity) Act 1964)
o Until recently, this special verdict obliged the judge to order D to be detained
indefinitely in a mental hospital
The key case of M’Naughten, where the D attempted to assassinate the prime minister due to
his delusions, provides that everyone is “sane unless proven otherwise”
, General Defences Criminal Law
o M’Naughten (1843) 10 C1 & F 200:
Radical and chartist supporter
Wanted to assassinate the prime minister, Robert Peel
Shot his private secretary, believing it to be Peel, in the back
o The rules are not binding as a matter of a strict precedent
o Nevertheless, the rules have been treated as authoritative ever since
o Rules;
Every man is presumed sane
To establish insanity, the D must show, on a balance of probabilities, that at the
time he was suffering from:
A defect of reason
Caused by a disease of the mind
He did not know the nature and quality of his act, or what he was doing
was wrong
Judge: the question whether the D was suffering from a defect of reason caused by a disease of
the mind is a question of law to be determined by the trial judge
Jury: the issue of whether the D knew the nature and quality of the act, or if he did know it,
whether he knew it was wrong, is a question of fact to be determined by the jury
Firstly, the D must suffer from a ‘defect of reason´ which requires an impairment of reasoning
This means being ‘deprived of the power of reasoning,’ rather than just ‘failing to use it’
Short periods of absent-mindedness are not sufficient - Clarke 1972:
o Old woman shoplifted
Can be permanent or temporary if recurrent e.g. Sullivan 1984 (epilepsy), D kicked V whilst
suffering from epileptic fit
In this scenario, D has a defect of reason because…
Secondly, the defect of reason must be due to a ‘disease of mind’
The disease must affect the ‘mind’ rather than the brain in the physical sense
The disease must affect the ordinary mental faculties of “reason, memory and understanding”
(per Devlin J in Kemp 1957)
This can be mental or physical, as in the case of Kemp (hardening of arteries)
o Kemp 1957:
Hardening of arteries
Attacked wife with hammer
Must be caused by an internal factor e.g. hyperglycaemia, as in the case of Hennessy, where D
failed to take insulin. However, in Quick, D took insulin but failed to eat afterwards, resulting in
hypoglycaemia (external factor – automatism)
o Hennessy 1989:
Failed to take insulin
Stole car
o Quick 1973:
