Criminal Defences

Insanity and automatism#

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Insanity versus automatism

Fig. 1The same illness can be insanity or automatism depending on whether the cause is internal or external.

Insanity and automatism are defences that deny that the defendant acted with a functioning, responsible mind, but they are sharply distinguished by their cause and their consequences. Insanity is governed by the M'Naghten Rules (1843). Every defendant is presumed sane; to establish insanity the defence must prove, on the balance of probabilities, that at the time of the offence the defendant was suffering from a defect of reason, caused by a disease of the mind, so that they did not know the nature and quality of their act, or did not know that what they were doing was wrong. 'Wrong' means legally wrong (R v Windle (1952)).

The crucial concept is 'disease of the mind', which is a legal, not a medical, term and turns on whether the cause of the impairment is internal to the defendant. Conditions arising from an internal cause count, however physical their origin: arteriosclerosis affecting the brain (R v Kemp (1957)), epilepsy (R v Sullivan (1984)), and diabetes causing high blood sugar where the defendant has not taken insulin (R v Hennessy (1989)) have all been held to be diseases of the mind, as has sleepwalking (R v Burgess). The successful defence results in the special verdict of 'not guilty by reason of insanity', after which the court has a range of disposal options.

Automatism (properly, non-insane automatism) is a complete defence resulting in an outright acquittal. It applies where the defendant's act was involuntary because of an external factor, and there was a total loss of voluntary control. In R v Quick (1973) a diabetic who committed an assault while suffering from low blood sugar caused by taking insulin (an external factor) could rely on automatism, whereas the internally caused high blood sugar in Hennessy was insanity - the same underlying illness produces different defences depending on the internal or external cause. A total loss of control is required: in Attorney-General's Reference (No 2 of 1992) (1994) reduced or partial control (a lorry driver 'driving without awareness') was insufficient. Self-induced automatism is restricted, especially for basic-intent offences.

For evaluation, the insanity defence is heavily criticised. The M'Naghten Rules date from 1843 and rest on an outdated understanding of mental illness; the legal test of 'disease of the mind' produces results that offend common sense, labelling epileptics and diabetics 'insane'; and the internal/external distinction that separates insanity from automatism can turn on fine and arbitrary differences (Hennessy compared with Quick). The Law Commission has recommended reform. A strong answer applies the M'Naghten Rules and the internal/external distinction accurately and can evaluate the case for reform.

The M'Naghten test for insanity

Fig. 2The defence must prove all three elements on the balance of probabilities.

Worked example

Worked problem question: insanity or automatism?

D, a diabetic, commits an assault while confused. In scenario (a) he had taken insulin and eaten too little (low blood sugar); in scenario (b) he had not taken his insulin (high blood sugar). Advise on the defence in each case.

Issue
Whether D's condition amounts to insanity or automatism in each scenario.
Rule / authority
Insanity (M'Naghten Rules) requires a disease of the mind from an internal cause (R v Hennessy - high blood sugar). Automatism requires an involuntary act from an external factor with a total loss of control (R v Quick - insulin-induced low blood sugar).
Application
In (a) the impairment is caused by the insulin, an external factor, so the defence is automatism, leading to acquittal (Quick). In (b) the impairment is caused by the untreated diabetes, an internal factor, so it is a disease of the mind and the defence is insanity (Hennessy).
Conclusion
The same illness yields automatism where the cause is external (insulin) but insanity where the cause is internal (the diabetes itself).

Result: The answer applies the internal/external distinction to allocate the correct defence, illustrating the criticism of the line.

Typical mistakes

Confusing insanity (internal cause; special verdict) with automatism (external cause; full acquittal), which can turn on the same illness.
Treating 'wrong' in the M'Naghten Rules as morally wrong; it means legally wrong (Windle).

Active revision

D, a diabetic, assaults V during a hypoglycaemic episode caused by taking too much insulin. Advise on the appropriate defence.

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for law (Department for Education) · AQA A-level Law (7162) specification (AQA)

Intoxication#

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Intoxication by drink or drugs is not strictly a defence; rather, it is relevant to whether the defendant, because of intoxication, actually formed the mens rea of the offence. The law distinguishes voluntary from involuntary intoxication and specific-intent from basic-intent offences. The leading authority is DPP v Majewski (1977).

Where the intoxication is voluntary (the defendant chose to take the drink or drug), it can be relevant only to offences of specific intent. If the defendant was so intoxicated that they did not form the specific intent required (for example the intention required for murder or for section 18 of the Offences Against the Person Act 1861), they are not guilty of that offence, but they will usually be guilty of a lesser basic-intent offence. In R v Lipman (1970) a defendant who killed under the influence of LSD lacked the specific intent for murder but was guilty of manslaughter, a basic-intent offence. For basic-intent offences (such as assault, battery, section 47 and section 20), voluntary intoxication is no defence at all: the recklessness involved in getting drunk supplies the fault, so the defendant is treated as having the necessary mens rea (Majewski).

Where the intoxication is involuntary - for example a spiked drink, or an unexpected reaction to prescribed medication - the position is different. Involuntary intoxication may be a defence if it means the defendant did not form the mens rea. But if the defendant did form the mens rea despite the involuntary intoxication, they are guilty: in R v Kingston (1995) a defendant whose drink had been spiked but who nonetheless formed the intent to commit the offence was convicted, because 'a drugged intent is still an intent'. A related point arises where the defendant takes a drug not known to cause aggression: in R v Hardie (1985) the defendant, who took valium (a sedative) to calm himself, was not to be treated as reckless merely for taking it, so the Majewski rule did not automatically apply.

For evaluation, the Majewski rule is a pragmatic compromise designed to protect the public from intoxicated offenders, but it is criticised for convicting a defendant of a basic-intent offence on the basis of the fault involved in getting drunk rather than any fault at the time of the actus reus, which strains the coincidence principle. The distinction between specific and basic intent is also criticised as uncertain. A strong answer classifies the intoxication and the offence, applies Majewski, and can evaluate the fairness of the rules.

Worked example

Worked problem question: voluntary intoxication

D becomes very drunk voluntarily and, in that state, kills V without any evidence of an intention to kill or cause GBH. Advise on the effect of the intoxication.

Issue
Whether D's voluntary intoxication affects liability for murder (specific intent) and manslaughter (basic intent).
Rule / authority
Voluntary intoxication is relevant only to specific-intent offences; if the specific intent was not formed, D is not guilty of that offence but is guilty of a basic-intent alternative (DPP v Majewski (1977); R v Lipman (1970)).
Application
Murder is a specific-intent offence. If D was so intoxicated that he did not form the intention to kill or cause GBH, he is not guilty of murder. But unlawful act manslaughter is a basic-intent offence, and voluntary intoxication is no defence to it, so D remains liable for manslaughter.
Conclusion
D's intoxication may negate the specific intent for murder but is no defence to manslaughter, following Majewski and Lipman.

Result: The answer classifies the offences by intent and applies the Majewski rule to each.

Typical mistakes

Treating voluntary intoxication as a general defence; it is no defence to basic-intent offences and only relevant to whether a specific intent was formed (Majewski).
Assuming involuntary intoxication is always a defence; if the defendant still formed the mens rea, they are guilty (Kingston).

Active revision

D, having drunk heavily, kills V in a drunken rage. Advise on how his intoxication affects his liability for murder and manslaughter.

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for law (Department for Education) · AQA A-level Law (7162) specification (AQA)

Duress and necessity#

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The Graham test for duress by threats

Fig. 3Duress requires a serious threat and satisfaction of both the subjective and objective stages.

Duress and necessity are defences of compulsion: the defendant commits the offence because they are compelled to do so by a threat or by the pressure of circumstances. Duress by threats applies where a person of ordinary firmness would have given in to a threat of death or serious injury. The test comes from R v Graham (1982), approved by the House of Lords in R v Howe (1987), and has two stages: first, was the defendant compelled to act because they reasonably believed they had good cause to fear death or serious injury (a largely subjective test qualified by reasonableness); secondly, would a sober person of reasonable firmness, sharing the defendant's relevant characteristics, have responded in the same way (an objective test)? R v Bowen (1996) explains which characteristics are relevant to the objective stage.

Duress by threats is subject to strict limits set out in R v Hasan (2005): the threat must be of death or serious injury; it must be directed at the defendant or someone for whom the defendant is responsible; there must be no safe avenue of escape and the threat must be imminent; and the defence is lost if the defendant voluntarily associated with criminals and foresaw, or ought to have foreseen, the risk of being subjected to compulsion. Crucially, duress is not a defence to murder (R v Howe (1987)) or to attempted murder (R v Gotts (1992)), because the law will not excuse the taking of an innocent life to save one's own.

Duress of circumstances applies the same Graham test but where the compulsion comes from the surrounding circumstances rather than a person's demand to commit a particular crime. In R v Conway (1988) and R v Martin (1989) defendants who drove while disqualified or dangerously to escape a perceived threat of death could rely on the defence. Necessity, as a general defence, is only rarely recognised, because of the danger of allowing individuals to break the law whenever they judge it beneficial; it was accepted in the exceptional circumstances of Re A (Conjoined Twins) (2001), where separating twins to save one was held justified, but R v Dudley and Stephens (1884) established that necessity is no defence to murder.

For evaluation, the compulsion defences reflect a difficult balance between compassion for a defendant acting under extreme pressure and the need to uphold the law and protect innocent victims. The exclusion of murder from duress (Howe) is defended as affirming the sanctity of life but criticised as harsh on a defendant who genuinely had no choice, and the Hasan restrictions have narrowed the defence considerably. A strong answer applies the two-stage Graham test and the Hasan conditions and can evaluate the limits on the defence.

Worked example

Worked problem question: duress by threats

D, threatened with serious violence to himself and his children unless he drives a getaway car in a robbery, does so. Advise on whether duress by threats is available.

Issue
Whether duress by threats excuses D's participation in the robbery.
Rule / authority
Duress by threats (R v Graham (1982); R v Hasan (2005)): a threat of death or serious injury to D or those he is responsible for, with no safe avenue of escape; the two-stage test asks whether D reasonably feared death or serious injury and whether a sober person of reasonable firmness would have given in.
Application
The threat is of serious injury to D and his children, satisfying the Hasan conditions if there was no safe escape and D did not voluntarily associate with the gang. On the Graham test, D reasonably feared serious injury, and a person of reasonable firmness might well have complied to protect their children. Robbery is not murder, so the defence is available for it.
Conclusion
Duress by threats is available and, if accepted, is a complete defence to the robbery.

Result: The answer applies the Graham test and Hasan conditions and correctly notes that duress is available for robbery (but not murder).

Typical mistakes

Allowing duress as a defence to murder; it is excluded for murder and attempted murder (Howe; Gotts).
Applying only the subjective first stage of the Graham test and forgetting the objective 'reasonable firmness' stage and the Hasan conditions.

Active revision

D commits a burglary because a gang has threatened to seriously injure his family if he refuses. Advise on whether duress is available.

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for law (Department for Education) · AQA A-level Law (7162) specification (AQA)

Self-defence and consent#

StandardAQA 7162/1 - DefencesDfE GCE Law subject content

Classifying the general defences

Fig. 4The defences fall into those denying capacity, those based on compulsion, and those that justify the act.

Self-defence is a complete defence: a person may use reasonable force to defend themselves or another, to protect property, or to prevent crime (the latter under section 3 of the Criminal Law Act 1967). The law is now largely clarified by section 76 of the Criminal Justice and Immigration Act 2008, which restates the common-law position. Two questions arise. First, was the use of force necessary? This is judged on the facts as the defendant honestly believed them to be, even if that belief was mistaken (R v Gladstone Williams (1987); section 76(4)), although a mistake induced by voluntary intoxication cannot be relied on (section 76(5)). Secondly, was the degree of force reasonable in the circumstances as the defendant believed them to be (section 76(6))? Force that is excessive or disproportionate is not reasonable, and the defence fails.

The law makes some allowance for the difficulty of the situation: a person acting in self-defence cannot be expected to weigh to a nicety the exact measure of their response, and evidence that they did only what they honestly and instinctively thought was necessary is strong evidence that the action was reasonable. In 'householder' cases - where a person uses force against a trespasser in their home - section 76(5A) provides that force is not to be regarded as reasonable if it was grossly disproportionate, a somewhat more generous standard considered in R (Collins) v Secretary of State for Justice (2016). Where the defence succeeds it results in a complete acquittal; where the force used is excessive, as in R v Martin (Anthony) (2002), the defence fails.

Consent is a defence to some non-fatal offences. A victim's genuine consent can make what would otherwise be an assault or battery lawful, which is why the ordinary contacts of everyday life and lawful sporting contact are not criminal. But as a matter of public policy, consent is generally not a defence to offences causing actual bodily harm or worse (Attorney-General's Reference (No 6 of 1980) (1981); R v Brown (1993), where consent to sado-masochistic injury was no defence). There are recognised exceptions where consent is valid despite serious harm, including properly conducted sports, reasonable surgical treatment, tattooing and piercing, and, as in R v Wilson (1996), consensual branding between spouses, which the court treated as akin to tattooing.

For evaluation, self-defence is generally regarded as striking a workable balance, protecting the citizen who defends themselves while requiring the force to be proportionate, though the householder provision and the standard of reasonableness remain controversial. The law on consent is criticised for inconsistency: the outcomes in Brown and Wilson are hard to reconcile, and the line between activities to which one can and cannot consent reflects contested moral judgements, connecting this topic to the debate on law and morality. A strong answer applies the two-stage self-defence test or the consent rules and can evaluate their coherence.

Worked example

Worked problem question: self-defence

D, honestly but mistakenly believing that V is reaching for a weapon to attack him, strikes V once to protect himself. Advise on self-defence.

Issue
Whether D may rely on self-defence where his belief in the need for force was mistaken.
Rule / authority
Self-defence permits reasonable force; necessity is judged on the facts as D honestly believed them, even if mistaken (R v Gladstone Williams (1987); s.76(4) Criminal Justice and Immigration Act 2008), and the force must be reasonable in those believed circumstances (s.76(6)).
Application
D honestly believed V was about to attack him, so the necessity of force is judged on that belief even though it was mistaken. A single punch to pre-empt a perceived armed attack is likely to be reasonable and proportionate in the circumstances as D believed them to be.
Conclusion
Self-defence is available: the force was necessary on the facts as D honestly believed them and was a reasonable response, giving a complete defence.

Result: The answer applies the two-stage self-defence test, judging necessity on the honestly believed facts under Gladstone Williams and section 76.

Typical mistakes

Judging the necessity of force on the true facts rather than on the facts as the defendant honestly believed them (Gladstone Williams; s.76(4)).
Assuming consent is a defence to any non-fatal offence; it is generally no defence to ABH or above (Brown), subject to the recognised exceptions.

Active revision

D, mistakenly but honestly believing V is about to attack him, punches V first. Advise on whether self-defence is available.

Active recall

Recall the key points — then reveal.

Sources: GCE AS and A level subject content for law (Department for Education) · AQA A-level Law (7162) specification (AQA)

Key points

Worked problem question: insanity or automatism?

Key points

Worked problem question: voluntary intoxication

Key points

Worked problem question: duress by threats

Key points

Worked problem question: self-defence

Sources

Criminal Defences

Key points

Worked problem question: insanity or automatism?

Key points

Worked problem question: voluntary intoxication

Key points

Worked problem question: duress by threats

Key points

Worked problem question: self-defence

Sources