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Criminal | Defences

Intoxication: Criteria

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Discuss the defence of intoxication

Intoxication does not provide a defence in itself. It is relevant in determining whether defendant has the required mens rea. If he lacks sufficient mens rea due to his intoxicated state then he may be found not guilty.

Nature of intoxication

The law distinguishes between voluntary and involuntary intoxication.


Voluntary intoxication occurs when defendant chooses, of his own free will to become intoxicated, with alcohol, illegal drugs or any intoxicants. Generally defendant should not be excused from consequences of their actions if voluntarily intoxicated because it is their responsible for being in such a state.

Defendant stabbed his wife to death. He bought a bottle of whiskey at same time as the knife and had drunk most of the bottle. It was found he had the necessary mens rea despite his intoxication and he was convicted of murder (Gallagher (1963)).

However, if it can be proved that the intoxication prevented the defendant from having the necessary mens rea the charge cannot be proved.


Involuntary intoxication covers situations where defendant did not know he was taking an intoxicating substance. For example if a drink is spiked or a prescribed drug has an unexpected effect.

It must be proved the intoxication prevented the defendant from forming the required mens rea. Intoxication causing lack of inhibition may not be sufficient (Kingston (1994)).

A defendant committed sexual offences after drinking homemade wine which was much stronger than he realised. It was held unanticipated strength of intoxicant does not make intoxication involuntary (Allen (1988)).

Non dangerous drugs may lead to involuntary intoxication. There is a distinction between dangerous drugs, ..where it is common knowledge.. [the taker] may become aggressive or do dangerous or unpredictable things... and non dangerous drugs, such as valium (Hardie (1985)).

Nature of intent

The law distinguishes between basic and specific intent offences. Principle is that intoxication can be a defence to crimes of specific intent and not to those of basic intent (Majewski (1976)).

Specific intent

Specific intent crimes are sometimes summarised as offences requiring mens rea. Murder and GBH S18 offence (under Offences Against the Person Act 1861 (OAPA 1861)) are considered specific intent crimes.

Defendants threw petrol over the victim and set fire to him, the victim died. Defendants found to be too drunk to have formed the necessary specific intent needed for mens rea for murder but were guilty of involuntary manslaughter, as that is a basic intent offence (Sheehan and Moore (1975)).

Basic intent

Difficulty arises with defining which offences are basic intent, it seems basic intent refers to general criminal intent, rather than any ulterior intent the defendant wants to achieve from his actus reus.

Voluntary intoxication provides no defence to basic intent crime, as the choice to become intoxicated is reckless. The defendant knows that there is a risk he will behave badly or criminally when intoxicated (Majewski (1976)).

Basic intent crimes can be summarised as offences requiring a mens rea of recklessness. Offences classified as basic intent: assault, battery, S47 and S20 offences (under OAPA 1861) and involuntary manslaughter.

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