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Defence of Insanity

Defence of Insanity

The defence of insanity is a defence that is applicable to all crimes. When a defendant is found to be insane or pleads insanity, the jury is directed to give a verdict of "not guilty by reason of insanity". This defence is often used in conjunction with other defences and generally is used in hope of diminishing responsibility for a crime. This is covered under section 2 of the Trial of Lunatics Act 1883. Historically, this would mean admittance to a secure accommodation or institutionalisation where release was only possible on authority of the Home Secretary. However, mandatory detention still applies where the penalty for the offence says so. For example, if someone committed murder, mandatory detention would be the sentence. In all other cases, it is at the discretion of the judge as stated under section 5 of the Criminal Procedure (Insanity) Act of 1964.

Insanity can be used at three point during the criminal process:

1. Insanity before trial

When an offender is in custody and is held as insane, the Home Secretary can detain him or her immediately in a mental hospital with the confirmation of state of mine from two doctors.

2. Unfitness to plead

If a defendant is unfit to plead, this can be raised by either the defence, prosecution or even the judge. Section 4 of the Criminal Procedure (Insanity) Act of 1964 states that a special jury can be composed to decide whether or not the defendant can stand trial. On a balance of probabilities, the jury decides if they are unfit to plead based on:

a. Understanding the charges
b. Deciding whether to plead guilty or not
c. Exercising his right to challenge jurors
d. Instructing solicitors and counsel
e. Following the course of the proceedings
f. Giving evidence in his own defence

Once a defendant is found unfit to please, a second jury is put together to establish whether or not they had the actus resus of the crime as stated under section 4 of the Criminal Procedure (Insanity) Act 1964. One the jury decides that the defendant did not commit the appropriate actus reus then they are acquitted. However, if they are found to hold the actus reus then the judge makes an order.

3. Insanity at the time of the offence

If one questions insanity at the time of the crime, it is determined through the "M'Naughten Rules". Under these rules, it must be established that at the time of the crime, the defendant was suffering from either:

a. A defect of reason

b. The defect of reason must be caused by a disease of the mind

i. Epilepsy

ii. Sleepwalking

iii. Hyperglycaemia from diabetes

iv. Arteriosclerosis

v. Or if not caused by an outside source, one can claim non-insane automatism (includes drinking or drugs)

c. The defect of reason must be such that the defendant did not know what he or she was doing or if he did, he did not know the act was wrong

à Defence of Non-Insane Automatism

Non-insane automatism acts a complete defence that absolves a defendant of all criminal liability. The difference from a claim of insanity is that there can be no power to detain a defendant in a mental hospital or have an order made against them. Essentially, when this type of claim is made, a person commits a crime when their actions are labelled as involuntary or not conscious of their actions due to external factors such as drugs or alcohol. The only imperative difference to pleading insanity and pleading non-insane automatism is the cause is from an external factor.

There are certain requirements for the defence of non-insane automatism:

1. There must be an involuntary action arising from an external source or a reflex action

2. The action must be completely involuntary

3. The automatism must not be self-induced

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