Topic 8Topic 8

Insanity

Topic 8Insanity

Introduction

In order to establish a defence on the grounds of

insanity, it must be clearly proved that at the

time of committing the act the party accused was

labouring under such a defect of reason, caused

by a disease of the mind, that he or she either

did not know the nature and quality of the act he

or she was committing, or did not know that what

he or she was doing was legally wrong.

Topic 8Insanity

Elements (1)

Defect of reason

The defendant must show that he or she was

suffering from a defect of reason; in other

words, that his or her ability to reason was

impaired. This is because the basis of the

defence is the defendant’s deprivation of the

power of reasoning.

Thus, a defendant who still possessed those

powers but failed to use them cannot be classed

as insane.

Topic 8Insanity

Elements (2)

Disease of the mindIn this context, ‘disease of the mind’ is a legal term and not a medical term. This has caused problems at times, since the legal definition does not always match the medical definition. This is apparent when looking at the types of conditions that the courts have accepted as constituting a disease of the mind. Following M’Naghten, delusional states are covered by this, but the inclusion of certain other conditions, such as arteriosclerosis, epilepsy and diabetes, has caused controversy.

Topic 8Insanity

Elements (3)Did not know the nature and quality of the act or that the act was wrongThe defect of reason caused by a disease of the mind must mean either that the defendant does not know the nature and quality of his or her act or, if he or she does, he or she does not know that the act is legally wrong. In terms of the ‘nature and quality of the act’, the defendant would be unaware of his or her actions. An example that is often given is of a defendant who thinks that he or she is cutting a loaf of bread but who is in actual fact cutting the victim’s throat.

If the defendant is aware of what he or she is doing, it is still possible to rely on the defence if he or she does not know that what he or she is doing is legally wrong.

Topic 8Insanity

Burden and standard of proof

The defendant must prove that he or she was suffering from insanity when he or she committed the offence. This must be proved on the balance of probabilities.

Topic 8Insanity

Effect

If a plea is successful, it leads to a special

verdict, and the defendant will be deemed ‘not

guilty by reason of insanity’. Until the

introduction of the Criminal Procedure Act 1991,

this automatically meant an indefinite hospital

stay, but now this only applies to murder. If the

defendant is charged with another crime, the

judge can make a hospital order, a guardianship

order, a supervision and treatment order, or an

absolute discharge.

Topic 8Insanity

Evaluation (1)

The burden of proof rests with the defendant

Critics have argued that it is unfair that the

burden is on the defendant to prove, on the

balance of probabilities, that he or she was

suffering from insanity. They say that this

undermines the notion that the defendant is

innocent until proven guilty by the prosecution.

Topic 8Insanity

Evaluation (2)

The use of a legal rather than a medical

definition

Perhaps the major flaw in this defence is that

the courts use a legal definition of insanity

rather than a medical one. In addition, the legal

definition dates from 1843 and fails to take

account of the huge medical advances that have

occurred since then.

Topic 8Insanity

Evaluation (3)

The rules are too broad

The classification of diabetics, epileptics and

sleepwalkers as insane has been criticised for

suggesting that those suffering from such

conditions are a danger to the public, whereas

this is far from the truth in the vast majority

of cases. Most people with such conditions are

able to control them by taking medication.

Topic 8Insanity

Evaluation (4)

The rules are too narrow

The defence can rule out those who are medically insane if they know the nature and quality of their act or that it is legally wrong but are nonetheless unable to stop themselves from committing it. Thus, those at whom the defence should be aimed are unable to rely on it.

Topic 8Insanity

Reform (1)

Place the burden of proof on the prosecution

The Butler Committee and the Criminal Law

Revision Committee have suggested that, since it

is part of mens rea, the burden of proof should

be reversed and placed on the prosecution rather

than the defendant.

Topic 8Insanity

Reform (2)

A new defenceCritics argue that the only way forward is to abolish the M’Naghten rules altogether. Instead, a new defence should be introduced. The Butler Committee suggested that this should apply to defendants with a mental disorder and should result in a verdict of ‘not guilty on evidence of a mental disorder’. This would avoid the defendant being labelled insane. Others suggest that there is no need for such a defence at all and that those suffering from insanity should be dealt with outside the criminal justice system.