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General defences - non-insane automatism

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Non-insane automatism

Alternative (and more correct name) for automatism.

Insane automatism

Alternative (and more correct name) for insanity.

Criminal Procedure (Insanity and Unfitness to Plead) Act 1991

If insanity is rejected automatism can be pleaded.  The difference between the two verdicts is not so important since the Act .

Reverse Burden of Proof

Defendant has the evidential responsibility to prove automatism.  Results in complete acquittal, and hence the courts are reluctant to entertain it save in exceptional cases (whereas with insanity the court has sentencing options despite the special verdict).


Muscles not controlled by the mind

Automatism is when the defendant is unable to control his muscles because they acted without the control of his mind.  In these circumstances he will not be held blameworthy Bratty v AG for Northern Ireland (1963) this is the leading case.

Lord Denning Bratty:

"…'automatism' - means an act which is done by the muscles without any control by the mind such as a spasm, a reflex action or a convulsion; or an act done by a person who is not conscious of what he is doing . . . [However] to prevent confusion it is to be observed that in the criminal law an act is not to be regarded as an involuntary act simply because the actor does not remember it... Nor is an act to be regarded as an involuntary act simply because the doer could not control his impulse to do it."

Must be external factor


There must be credible evidence of an 'external factor' for example a blow to the head, skidding on ice, being stung by bees, an anaesthetic. Which is unlikely to recur

(Quick (1973) hypoglycaemia caused by the insulin he had taken and the fact that he had drunk alcohol and not eaten, all external factors, and so he could successfully raise the defence of automatism.

Limits to what is ‘external factor’

Hennessy (1989) argued that hyperglycaemia was caused by failure to take insulin, which in turn was caused by stress and depression, which Lord Lane said were not external factors.

Hennessy’s hyperglycaemia was triggered by an internal factor (his diabetes))

'In our judgment, stress, anxiety and depression can no doubt be the result of the operation of external factors, but they are not, it seems to us, in themselves separately or together external factors of the kind capable in law of causing or contributing to a state of automatism.'

The Court of Appeal pointed out that they were prone to recur and lacked the feature of novelty or accident. The kind of external factors the law required would be something like a blow to the head, or an anaesthetic.’

Total loss of control

To succeed the defence must show that the automatism caused a total loss of control. 

Impaired, reduced or partial control by the defendant will not found a defence of automatism (AG s Reference No 2 of 1992 (1993))

Must be a total loss of control

Broome v Perkins (1987) D could remember nothing about a journey, he was able to exercise some voluntary control over his movements, he had not been acting in an entirely involuntary manner.

Similarly in Attorney General's Reference No 2 1992 (1993), another dangerous driving case followed Broome v Perkins. 

D had been put into a trance-like state by the repetitive vision of the long flat road which reduced, but did not eliminate, awareness of what he was doing.

Internal factors are insanity


Where the cause of the behaviour is 'internal' such as a 'disease of the mind' or a disease of the body the relevant defence will be that of insanity rather than automatism (Hennessy (1989))


Looks like automatism but in law is insanity. Sullivan, R v (1983)

Self-induced automatism

Available for specific intent offences even if self induced

If, for example, the defendant takes dangerous drugs, and so is at fault in bringing about the autonomic state, he has a defence to crimes of 'specific intent', but not to those of 'basic intent'. Lipman (1970); Bailey (1983).

Not available for basic intent crimes; if it is D’s fault

Normal rules of intoxication apply.  Drinking alcohol or taking dangerous drugs, do not provide a defence for usual policy reasons.

Self-induced, e.g. by not taking insulin (but not alcohol) can be relied upon, but not if they knew it would happen

Bailey, R v (1983) D a diabetic injured his ex-girlfriend's new boyfriend during a hypoglycaemic attack. Feeling unwell beforehand, he had eaten some sugar but no other food.


Held: Self-induced automatism (other than that caused by drink or drugs) can provide a defence if the accused's conduct does not amount to recklessness, taking into account his knowledge of the likely results of anything he has done or failed to do.

If D did not realise failing to eat would cause automatism

In Bailey's case, this meant that he would have a defence if he did not realize that failing to eat would put him into a state in which he might attack someone without realizing it.

If D did realize failing to eat would cause automatism

If he was aware of this, and still failed to eat, he was reckless and the defence ought not to be available.

Unexpected reaction to soporific or sedative drugs may allow defence of automatism

If D takes drugs which normally have a soporific or sedative effect and D’s reaction to the drug was unexpected, and then commits a crime involuntarily, the defence of automatism may be available.

Even non prescribed drugs, may allow defence of automatism

In Hardie (1984), a person whose condition of automatism was due to taking Valium (a tranquillizer) could rely on the defence, even though a doctor had not prescribed the drug.

Mens rea or actus reus?

Strict liability

Defence applies it there is no control over actus reus, obviously mens rea is irrelevant, because strict liability offences require no mens rea.

Specific intent

Goes to mens rea, rules of intoxication apply

Basic intent

Goes to mens rea, can be a defence provided D's conduct is not reckless in bringing about the autonomic state; basic intent offences can be committed recklessly.

Criticisms and proposals for reform  (this is no longer part of the syllabus)

Irrational distinctions

Distinguishing between internal and external causes has been criticized as leading to absurd and irrational distinctions - such as that drawn between Hennessy and Quick.

The main reason given for the difference is that automatism caused by an internal factor, namely a disease, is more likely to recur than such a state caused by an external factor. This may be true of a comparison between an automatic state caused by a long-term mental illness, and one caused by a blow to the head, but as the cases on diabetes show, the distinction can be tenuous, to say the least.

Clarkson and Rearing

Suggest that psychiatrists believe that, even when unconscious, people can act voluntarily.

Robert White

Recorded an incident during the Second World War, in which a soldier set off to take a message to a place where there was a lot of fighting and enormous danger. Some hours later, he found himself pushing his motorcycle through a coastal town nearly a hundred miles away, but had no idea how he had got there. Thoroughly confused, he gave himself up to the military police, who used hypnotism to try to discover what had happened. Under hypnosis, the soldier recalled that he had been knocked over by an explosion, got back on his bike and headed straight for the coastal town, asking directions and studying road signs in order to get there. Despite his genuine amnesia, he had acted rationally throughout; the amnesia had simply enabled him to do what he wanted to do, which was to escape without having to face up mentally to the consequences of being a deserter.

The implication of this argument is that perhaps automatism should not give rise to a complete acquittal. Automatism rests on the idea that the person acts without thought, but if it is the case that many everyday actions are carried out automatically without there being any distinctive thinking process involved, this situation is not as exceptional as the defence suggests.

The draft Criminal Code

The draft Criminal Code proposes maintaining the law on automatism as it stands, because the public interest is best served by the complete acquittal of anyone who acts while in a condition of non-insane automatism.

While this may be reasonable for the one-off offender, it offers no public protection against someone who is prone to recurring states of automatism through some external factor - though in this case the accused's own awareness of the dangers might lead to liability being imposed, on the grounds that he or she has behaved recklessly.

Abolition of the external/internal distinction

The distinction between internal and external causes could be abolished. Reform of the insanity defence to bring it in line with medical thinking would go some way towards this; behaviour that was allegedly automatic but clearly did not fall within medical definitions of insanity could then be considered solely in the light of the danger of recurrence, and the element of recklessness in the accused's behaviour.

Lord Goddard in Hill v Baxter [1958] (quoting Humphreys J in Kay v Butterworth (1945)


"I do not mean to say that a person should be made liable at criminal law who, through no fault of his own, becomes unconscious while driving, as, for example, a person who has been struck by a stone or overcome by a sudden illness , or when the car has been put temporarily out of his control owing to his being attacked by a swarm of bees..." I agree that there may be cases where the circumstances are such that the accused could not really be said to be driving at all. Suppose he had a stroke or an epileptic fit, both instances of what may properly be called Acts of God; he might well be in the driver's seat even with his hands on the wheel but in such a state of unconsciousness that he could not be said to be driving. A blow from a stone or a swarm of bees I think introduces some conception akin to "novus actus interveniens".

  • So Automatism is something external that the defendant does not bring upon himself.

  • Not one bee, but a swarm, because it has to be total loss of control

  • If the defendant loses control because of an illness, that is, some internal factor, he can only plead insanity

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