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Criminal incapacity

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Incapacity does not technically provide a defence to a crime, it negates the mens rea instead. There are 4 types of incapacity: intoxication, insanity, automatism and diminished responsibility.


Intoxication refers to alcohol or other substances impairing a defendant’s capacity. There are two types of intoxication: voluntary and involuntary, the former where the defendant chooses to consume alcohol or another impairing substance, and the latter where intoxication is forced. This defence places an evidential burden on the defendant. Once the judge has been passed with some evidence, the legal burden will be on the prosecution to prove that the defence cannot be made out. If intoxication is successfully pleaded, the offence committed will be reduced to a lesser offence.

Voluntary intoxication

In the words of Glanville Williams, it would be inimical to the safety of us all if intoxication provided a general exemption from criminal liability. Therefore, as illustrated by the legendary case of Lipman [1970], policy requires that intoxication does not automatically prevent criminal liability.

Starting from the assumption that alcohol will not assist a defendant, if an offence is one requiring a ‘specific intent’, a jury is entitled to consider whether a defendant had the relevant mens rea of the defence, taking into account his consumption of alcohol. If alcohol negated the mens rea, the defendant will be absolved from liability. Conversely, if the offence is one of ‘basic intent’, the defendant’s intoxication must be ignored, generally making it easier for an intoxicated defendant to be found guilty of that offence.

Specific intent

R v Beard [1920] provided the first mention of the term ‘specific intent’ in a case where the defendant attacked a 13 year old girl with the intent to rape her. This case marked a change in attitude, treating intoxication as a mitigating factor as opposed to an aggravating factor. Where alcohol negates the mens rea of an offence by reducing the defendant’s capacity, it was said that the crime should be reduced to a lesser crime. For example, murder would be reduced to manslaughter.

  • R v Sheehan & Moore [1975] – 2 drunken students poured petrol over the victim, set it alight and caused death. Lord Lane found that as a general rule, drunken intent is still intent.
  • R v Heard [2008] – sexual assault of a police officer on the ay to a hospital. This case defined specific intent as an intention to do an act beyond the act actually committed (an outcome view). As there was no further act or purpose for sexual assault, the offence was one of basic intent, in which alcohol was to be ignored and the defendant found guilty
  • R v Gallagher [1963] – dutch courage will negate the leniency of specific intent (Lord Denning)

A specific intent crime cannot be proved by recklessness. Examples include murder, theft, GBH with intent, attempts and burglary with intent.

Basic intent

According to R v Majewski [1977], in which the defendant attacked a police officer, where a defendant commits an offence of basic intent, even if nearly insane, that intoxication must be ignored. This was justified with the idea of ‘prior recklessness’, where in choosing to become intoxicated, a defendant realises the risk of any future crimes he might commit. Perhaps basic intent refers to a ‘moral equivalent’ of recklessness.

  • R v Richardson [1999] – drunken students tipped one peer over a balcony, convicted under s 20 OAPA 1861 (GBH, a basic intent crime). The correct jury direction was said to be: if the defendant would have seem the risk of some harm had he not been drinking, guilty (but for test)
  • R v Caldwell [1982] – Lord Diplock – ‘would have been obvious’ if sober

The distinction between basic and specific intent crimes is based on policy, as sexual offences require a specific intention, but are classed as basic intent crimes. The same is true of criminal damage with intent or recklessness as to endangering life under s 1(2) of the Criminal Damage Act (CDA) 1971, as illustrated by R v Caldwell, Harris & McGhee [2013].


According to s 76(5) of the Criminal Justice and Immigration Act (CRIMJIM) 2002, self defence cannot be relied on where intoxication is to blame against. This is illustrated by R v Hatton [2006], where a murder conviction could not be negated by self-defence after the defendant had consumed 20 pints of beer.

Specific statutory provisions may provide defences, however. In Jaggard v Dickinson [1981], a defendant trying to break into a house under the mistaken belief that it was his friend’s house could be defended on the basis of an honest belief lawful excuse under s 5(2)(a) CDA 1971.

The Law Commission is in favour of codifying Majewski, Richardson and Hatton (above).

Involuntary intoxication

As a general rule, involuntary intoxication will not displace the normal rules of proof in criminal law. If the involuntary intoxication negated the defendant’s mens rea, no offence will have been committed. But in R v Kingston [1995], as mens rea was still found by a jury, even though the defendant was involuntarily intoxicated at the hands of another person, he was found guilty of indecent assault.

Misuse of medicines

Where medicines, as opposed to alcohol, causes intoxication, the same rules apply. In R v Bailey [1983], as the defendant realised the risks associated with a diabetic imbalance, he was guilty when using a metal bar to injure his rival in love. Conversely, where, in R v Hardie [1984], the defendant did not realise that an excess of valium (a calming drug) could cause aggressive behaviour, he could not be guilty of causing criminal damages. Commentators have suggested that a much harsher line should be taken: those who take drugs and who are reckless as to their consequences should not be treated more favourably.


The Law Commission have suggested, in their report LC314 (2009), that basic intent should be redefined to crimes where there is no integral fault element, and specific intent to crimes with consequences intended, known or believed. Although the Law Commission agrees that a mistake as to self-defence should not be available to a voluntarily intoxicated defendant, they suggest a defence where the defendant would have made the same mistake of fact if not intoxicated.

Non-insane automatism

The defence of automatism refers to an act committed without the control of the mind. Where self-induced, only the defence of intoxication will be available. The defence may be raised by way of an evidential burden and, if not legally disproved by a prosecution, will lead to a complete acquittal. According to Lord Denning in Bratty v Attorney General for Northern Ireland [1963], an involuntary act should not be punishable without the control of the defendant’s mind. In Bratty, an epileptic woman strangled the victim, which was classed as outside of the scope of non-insane automatism, to be put into the ‘insanity’ categorisation as epilepsy was treated as a disease of the mind. Lord Denning laid out 3 requirements for the offence: a total loss of control, no fault, and an external and transitory cause.

Total loss of control

  • Broome v Perkins (1987) – a sudden hypoglycaemic attack whilst driving did not constitute a total loss of control as the defendant could still control his car in part
  • Attorney General’s Reference (No 2 of 1992) [1994] – in the situation where a lorry driver drives into the back of a stationary car, killing its occupants, as a result of the driver ‘driving without awareness’, as the condition is not one of automatism, as the driver still has some control
  • R v Coley, Harris & McGhee [2013] – Coley order xanax online overnight (brief Cannabis psychotic episode) stabbed neighbour; McGhee (tinitus – alcohol+drugs mix) ABH + stab, had control; McGhee wounding
  • Rumbold & Wasik (commentators), (old) Law Commission – lack of effective control to be preferred, now disregarded

No fault

  • R v Quick [1973] – a conviction was quashed where a judged ruled as a matter of law that ABH following an insulin balance constituted automatism. The question should have been left to the jury. Non-insane automatism will not be found where self-induced or objectively reasonably foreseen.
  • R v Bailey [1983] – a diabetic defendant failed to eat properly and consumed alcohol. His conviction for striking his rival in love with a metal bar was held to be secure, as the he was subjectively at fault in failing to eat properly. There was evidence that the defendant had intended the act all along.

External and transitory cause

Evidence that a state of automatism is likely to recur or is internally caused is more likely to lead to a conclusion that the defendant is insane, and was not in a temporary state of non-insane automatism. If this is the case, insanity (insane automatism) should be considered instead (below). Glanville Williams suggests that an external cause is not a ‘disease of the mind’.

  • R v Bingham [1991] – A diabetic, during a state of hypoglycaemia, stole a can of coke and sandwiches in a shop (whilst having £90 in his pocket). A causing excess of insulin was classed as an external cause, allowing automatism (as opposed to the internal condition of diabetes)
  • R v Hennessy [1989] – A diabetic who was depressed, stressed and anxious following his wife’s abandonment, failed to take medication. He took a motor vehicle without consent whilst in a state of hyperglycaemia. Automatism was not available as a defence as the state was caused by the internal condition of diabetes.


Insanity places a legal burden of proof on a person who raises it as a defence. If proven, it will give rise to a ‘special verdict’, which is often a hospitalisation order for an indefinite period of time. It is open to a prosecution to raise the defence if they wish to see the defendant served with such an order, according to R v Sodeman [1936]. The legal burden associated with this defence likely only exists as the defence existed prior to the rule in R v Woolmington [1935].

According to Ashworth, it is presumed that people are sane, and according to Lord Diplock in R v Sullivan [1984], special verdicts protect society from the recurrence of harmful behaviour. In Bratty v Attorney General of Northern Ireland [1963], Lord Denning confirmed that where a mental disorder is prone to recur, a special verdict should be issued, and the defendant should not be acquitted.

Bar to trial

Insanity covers a wide range of defendants, and it is possible that some defendants will not even be fit to stand trial. Under the Criminal Prodecure (Insanity) Act 1964, s 4A and s 5, where a defendant is disabled by decision of a jury, a short procedure may be used to obtain a special verdict.

  • R v Pritchard (1836) – a defendant’s fitness to stand trial will involve a consideration of his ability to take part: will he understand his plea, available defence, details of evidence and the procedure? R v M [2003] upheld this case.
  • R v Robertson [1968] – paranoia did not stop a trial
  • R v Podola [1960] – a defendant’s lack of ability to recall a defence did not stop his trial
  • R v Walls [2011] – aids to communication may exist


The legendary case on insanity is R v McNaughten (1843), in which the House of Lords found the killer of the current Prime Minister’s secretary to be insane following his claim that he was being persecuted by Conservative politicians. The case stated that:

“on the ground of insanity, it must be clearly proved that, at the time of the committing of the act, the party accused was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know he was doing what was wrong.”

Defect of reason

According to R v Clarke (1972), a defect of reason must be something more than a moment of confusion or absent mindedness; preventing the defence being pleaded against a conviction for shoplifting.

Disease of the mind

This is the key point to proof of insanity:

  • R v Sullivan [1984] – epilepsy is (regrettably) a disease of the mind. A disease of the mind refers to a impairment, permanent or transitory, resulting from an organic or functional cause, leading to the defending being unaware of what he is doing.
  • R v Kemp [1957] – insanity where a husband’s brain arteries hardened, and he killed his wife
  • R v Burgess [1991] – violent sleepwalking, no recurrence, but still insane, so sentencing discretion until shortly after this case was decided
  • R v Hennessy [1989] – insanity is too broad, but must protect society from recurrence
  • Law Commission 2013 – “insanity” should be re-worded to “not criminally responsible by reason of recognised medical condition”

Nature and quality of act unknown

  • R v Sullivan [1984] – defined this requirement as ‘not knowing what he’s doing’

Doesn’t know (legally) wrong

  • R v Windle [1952] – the defendant told police that he expected to be hanged after killing his wife by overdose on aspirin. The requirement of a defendant not knowing that what he did was legally wrong must involve the lack of knowledge of a legal wrong, rather than any other wrong. As the defendant knew that the act was legally wrong, he could not plead insanity
  • Law Commission 2013, R v Johnson [2007], Latham LJ – regret that the test involves the lack of knowledge of a legal wrong, wishing for a moral wrong test instead (which would make the defence easier to plead)


According to R v Oye [2013], both intoxication and insanity may not assist with a plea of self-defence. A defendant could not plead self-defence to the killing of police officers (who he thought were vil spirits) where intoxicated.

Conflicting defences

According to Coley [2013], the taking of cannabis will only allow for an intoxication to assist a defendant, not automatism. In Harris [2013], a defendant could not rely on either insanity or intoxication where he suffered severe side-effects after stopping drinking alcohol suddenly. In McGhee [2013], a combination of prescription drugs and alcohol allowed only intoxication to assist in negating the defendant’s criminal damage charge.

Diminished responsibility

As a final type of incapacity, Section 2 of the Homicide Act 1957 historically provided a defence of diminished responsibility, which allowed a murder conviction to be reduced to a manslaughter conviction if the defendant was suffering from an abnormality of the mind substantially impairing his mental responsibility. There were 2 key issues with this defence:

  • Terminology used was unconnected to that used in the medical profession
  • ‘Substantial’ was too vague to be left to juries

Section 52 of the Coroners and Justice Act 2009 substituted this defence, allowing diminished responsibility where an abnormality of mental functioning resulting from a recognised medical condition substantially impairs a defendant’s understanding of his conduct, formation of rational judgment or exercise of self-control.

According to R v Brenna [2014], where there is clear, un-contradicted evidence satisfying this reformed partial defence, a judge may remove murder from a jury’s consideration. R v Dowds [2012] confirms that this reform is not intended to apply to cases of self-induced intoxication.

Next: Self-defence, duress and necessity

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