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Defence of insanity
 
 
 
 
 
 
The defence of insanity is a general defence which is available to all crimes. Where a defendant is found to be insane, the jury are directed to give a special verdict of 'not guilty by reason of insanity' under s.2 of the Trial of Lunatics Act 1883. This previously meant automatic admittance to secure accommodation. Release was only possible on authority of the Home Secretary. This often resulted in lifetime institutionalisation. Mandatory detention still applies where the penalty for the offence is fixed by law eg murder. In all other cases detention is at the discretion of the judge under s.5 Criminal Procedure (Insanity) Act 1964.
 
 
The defence of insanity is unique in that it may be raised by the prosecution and judge in addition to the defence. Indeed, it is generally the defence seeking to avoid a finding of insanity and often the defendant will change a plea to guilty to avoid a finding of insanity. The defence has declined in importance and use since the abolition of the death penalty and the introduction of the defence of diminished responsibility in relation to murder.
 
 
 
 
 
 

 
Insanity is relevant at three points:
 
 
1. Insanity before trial
 
2. Unfitness to plead
 
3. Insanity at the time of the offence 
 
 
 
 
 
1. Insanity before trial
 
Where the offender is in custody but is obviously insane, the Home Secretary has the power to detain him immediately in a mental hospital. Confirmation from two doctors of the offender's state of mind is required.
 
 
 
 
 
2. Unfitness to plead
 
 
The question of unfitness to plead may be raised by the defence, prosecution or the judge. A special jury is empanelled to decide if the defendant is unfit to plead under s.4 Criminal Procedure (Insanity) Act 1964.The jury can make a finding of unfitness to plead if, on a balance of probabilities, any one of six things that was beyond the appellant's capabilities:


(1) understanding the charges;
(2) deciding whether to plead guilty or not;
(3) exercising his right to challenge jurors;
(4) instructing solicitors and counsel;
(5) following the course of the proceedings;
(6) giving evidence in his own defence.

 

 
R v Pritchard (1836) 7 C&P 303  Case summary
 
 
 
M (John) [2003] EWCA Crim 3452 Case summary
 
 
 
 
 
If the defendant is found to be unfit to plead, a second jury is empanelled to establish if the defendant has committed the actus reus of the crime under s.4A Criminal Procedure (Insanity) Act 1964. If the jury is of the opinion that the defendant did not commit the actus reus, the defendant is acquitted and that is the end of the matter. If, however, the jury are of the opinion that the actus reus was committed by the defendant, the judge may make an order under s.5 Criminal Procedure (Insanity) Act 1964.
 
The trial under s.4A can not result in a criminal conviction and is therefore outside the scope of Art 6 ECHR. Furthermore, as it is solely concerned with the actus reus of the offence the defence of diminished responsibility can not be raised:

 
 
 
 
 
 
 
3. Insanity at the time of the offence
 
 
The question of insanity at the time of the offence is determined by application of the M'Naghten rules.
 
 
 
M'Naghten [1843] UKHL J16   Case summary
 
 
Under the M'Naghten rules, it must be established that at the time of the offence the defendant was suffering from:
 
 
 
i). A defect of reason
 
ii). The defect of reason must be caused by a disease of the mind
 
iii). The defect of reason must be such that the defendant did not know what he was doing or, if he did know, he did not know the act was wrong.
 
 
 
i). A defect of reason
 
 
For a finding of insanity, the defendant must suffer from a defect of reason. Mere forgetfulness or absent mindedness is not sufficient:
 


 
 
 
ii). The defect of reason must be caused by a disease of the mind
 
 
Insanity requires the defect of reason to be caused by a disease of the mind. The courts have interpreted this widely as to include any physical disease which affect the mental functioning will be classed as a disease of the mind. Disease of the mind has been held to include:
 
 
 
Arteriosclerosis - R v Kemp (1957) 1 QB 399  Case summary
 
 
 
Epilepsy - Bratty v A-G for NI[1963] AC 386 Case summary
 
 
 
             - R v Sullivan [1984] AC 156  Case summary


 
 
Sleepwalking - R v Burgess [1991] 2 WLR 1206 Case summary
 
 
Hyperglycaemia arising from diabetes - R v Hennessy [1989] 1 WLR 287  Case summary
 
 
  
 
Where the defect of reason is caused by an outside source, this will not lead to a finding of insanity, but may give rise to the defence of non-insane automatism.   This has lead to an unfortunate consequence in relation to diabetics since if a diabetic commits an offence whilst suffering from hyperglycaemia, a state arising from too much blood sugar as a result of not taking insulin, they will be classed as insane. However, if the diabetic takes too much insulin resulting in a hypoglycaemia state, this will be classed as an outside source resulting in a finding of non-insane automatism. Non-insane automatism is a complete defence leading to the acquittal of a defendant with no hospital order attachments.
 
 
R v Quick [1973] 3 WLR 26   Case summary



 
 
External factors such as drink or drugs also may lead to a finding of non-insane automatism:
 
 
 
R v Burns 58 Crim App R 364 Case summary 
 
 
 
 
 
R v Roach [2001] EWCA Crim 2698  Case summary

 

 
 
iii).The defect of reason must be such that the defendant did not know what he was doing or, if he did know, he did not know the act was wrong.
 
 
 
If the defendant knew that what he was doing was unlawful no finding of insanity can be made even if they did not believe it was morally wrong:
 
 
R v Codere (1916) 12 Cr App R 21 Case summary
 
 
 
R v Windle [1952] 2QB 826 Case summary
 
 
 
 
R v Johnson [2007] EWCA Crim 1978 Case summary
 
 
 Insanity in criminal liability