7. Intoxication and mistake

Crimes of specific intent are those in which, as to at least one element, the prosecution must prove intention and nothing less. Murder, wounding with intent under section 18 of the Offences against the Person Act, burglary and attempt are the examples. Crimes of basic intent are those in which intention or recklessness is enough. Malicious wounding under section 20, and assault occasioning actual bodily harm under section 47, are the examples. The categories are not closed. DPP v Majewski is the classification.

Beard's case states the limit. Intoxication is relevant only if it rendered the accused incapable of forming the mens rea. Voluntary intoxication can negative a specific intent. It is not a defence to a crime of basic intent, and it does not help where the specific-intent crime has a basic-intent alternative, such as manslaughter on a charge of murder. A drunken intent is still an intent. That is Sheehan.

Dutch courage does not help. Gallagher decided to kill his wife, bought a knife and whisky, drank the whisky, and killed her. He was sane and sober when he formed the intention. Lord Denning said the wickedness of the mind before the drink, coupled with the act he intended and did, is enough. The same answer bars a person who drinks in order to bring on a state he will then call insanity. The mens rea here comes before the act. That is the exception to the rule that the two must be contemporaneous.

Involuntary intoxication can negative mens rea whether the crime is one of specific or of basic intent, but not if he still formed the intent and acted on it. Kingston's drinks were laced. He indecently assaulted a boy of fifteen and admitted that he intended the assault. An intoxicated intention was still an intention. The fact that he would not have done it if sober went to mitigation, not to guilt. A person is not to be treated as reckless for taking a drug that is not generally known to cause aggression. Hardie distinguishes sedatives such as valium from alcohol and from drugs known to make conduct unpredictable. If he is still aware of what he is doing, partial intoxication is no defence.

Mistake of fact is not a separate defence sitting beside the definition. If the definition requires mens rea, and the mistake means he did not have it, the prosecution has not proved the offence. The mistake need not be reasonable. It must be honest. DPP v Morgan is the case. Morgan told three men that his wife would resist as a pretence. They had intercourse without her consent. An honest belief in consent meant they lacked the intention the offence requires. Reasonableness is evidence of whether the belief was honest. It is not a legal requirement. Kimber applies the same rule to indecent assault. Smith applies it to criminal damage. A tenant who removed wiring and boarding he had installed, honestly believing the fixtures were his, was not guilty, even though in law they belonged to the landlord.

Where the offence does not require mens rea, a mistake must be honest and reasonable. Bigamy is in that class. Tolson is the authority. The two rules sit side by side. Do not apply the reasonable-mistake rule to a crime whose definition already requires intention or recklessness.