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This Legal Guidance is intended to assist prosecutors when dealing with issues of intoxication relating to suspects/defendants.

General Principle

Intoxication, whether voluntary or involuntary, is not a defence per se. However, where a person is intoxicated through drink or drugs and commits a crime, the level of intoxication may be such as to prevent that person from forming the necessary mens rea of the crime.

Intoxication: Involuntary versus Voluntary

Involuntary Intoxication

Involuntary intoxication most commonly arises in cases where the suspect/defendant claims that their food or drink has been ‘spiked’ without their knowledge.

However, involuntary intoxication is not a defence when the defendant (despite or because of the intoxication) formed the necessary mens rea at the time of committing the offence. Thus, where the drink or drug removed the inhibitions of the defendant so that he acted in a way which he would not have done if sober, he will still be guilty if he was able to, and did in fact, form the required mental element of the offence: R v Kingston [1995] 2 A.C. 355. 

Ignorance of the strength or effect of a drink or other intoxicating drugs that a defendant has voluntarily consumed, does not make the subsequent intoxication involuntary: R v Allen [1998] Crim. L.R. 698 CA.

Voluntary Intoxication

Voluntary intoxication occurs as a result of the voluntary consumption of alcohol or drugs provided that, in the case of a drug, it is well known for being liable to cause unpredictability or aggressiveness. In R v Bailey [1983] 2 All ER 503 and R v Hardie [1985] 3 All ER 848, the Court of Appeal formulated the principle that there are two categories of drug: ‘dangerous’ (e.g. LSD, amphetamine, etc.) and ‘non-dangerous’ (e.g. ‘Valium’).

Knowingly taking a ‘dangerous’ drug counts as voluntary intoxication. Knowingly taking a ‘non-dangerous drug’ may also count as voluntary intoxication, depending on the subjective appreciation of the likely effects of the drug in the quantity and circumstances in which it was consumed.

Intoxication: Specific and Basic Intent

Voluntary intoxication is never a defence to a crime of basic intent.

However, where the defendant has voluntarily put himself in the position of being intoxicated to the extent that he is incapable of forming the mental element of the offence, this will amount to a defence in respect of a crime of specific intent.

This principle is subject to the caveat that a drunken intent is still an intent: R v Sheehan and Moore (1975) 60 Cr App R 308.

NB: A person who deliberately makes himself intoxicated in order to give himself sufficient courage to commit an offence cannot raise a defence based on such intoxication, even to a crime of specific intent: AG for Northern Ireland v Gallagher [1963] AC 349.- (The ‘Dutch courage rule’).

The distinction between crimes of specific intent and crimes of basic intent was drawn in DPP v Beard [1920] AC 479 and affirmed in DPP v Majewski [1977] AC 443 HL. The terms ‘basic intent’ and ‘specific intent’ have since been defined in different ways.

Crimes of specific intent have sometimes been stated to include crimes where the offence can only be committed intentionally i.e. where recklessness will not suffice (e.g. murder): R v Caldwell [1982] AC 341 HL.

Another definition often used is where the offence requires an ulterior intent i.e. one which requires proof of an intent which goes beyond the prohibited act (e.g. criminal damage with intent to endanger life): R v Heard [2007] 3 WLR 475.

Crimes of specific intent have been held to include:

  • Murder
  • S.18 wounding/GBH with intent
  • Arson/criminal damage with intent to endanger life 

Crimes of basic intent have been held to include: 

  • Common assault
  • S.47 assault occasioning actual bodily harm
  • Manslaughter
  • Assault on a police officer in the execution of his duty
  • S.20 wounding/GBH
  • Taking a conveyance without the owner’s authority
  • Arson/criminal damage
  • Arson/criminal damage being reckless as to whether life would be endangered
  • Sexual assault (notwithstanding the fact that “intentional” touching of the complainant by the defendant is an essential element of the offence)


Drunken mistakes are generally no defence to crimes of basic intent: R v Fotheringham (1989) 88 Cr App R 206. 

However, where a statute (e.g. Section 5(2)(a) Criminal Damage Act 1971) provides a limited defence based on a genuine belief, the mistake may be relied on even where the mistake was induced by voluntary intoxication: Jaggard v Dickinson [1981] 1 QB 527. 


Where a defendant is labouring under a mistaken belief that they are under attack and acting in self-defence, they cannot rely on such mistaken belief where it was induced by voluntary intoxication. This applies to crimes of both basic intent and specific intent: R v Hatton [2006] 1 Cr App R 16.


Disinhibition as a result of consuming drink and/or drugs is not automatism. Furthermore, automatism is not available to a defendant who has induced an acute state of involuntary behaviour as a result of his own voluntary consumption of intoxicants: R v Coley; R v McGhee; R v Harris [2013] Crim. L.R. 923 CA.

In Scotland, the High Court of Justiciary has held that automatism cannot be established as a defence to a charge of driving with excess alcohol upon proof of a transitory state of parasomnia (sleep-walking) resulting from and induced by deliberate and self-induced intoxication: Finegan v Heywood, The Times, May 10, 2000. Although this decision is not binding upon the courts in England and Wales, it is a persuasive authority.

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