Intoxication

The Law Commission's official report to Parliament, Intoxication and Criminal Liability, frames the entire topic around a single question: whether, because of the effects of an intoxicant, the defendant lacked the subjective fault (state of mind) required by the definition of the offence charged. It is not simply the fact of intoxication that provides a defence — the report is explicit that the simple fact that D was voluntarily intoxicated at the time he or she allegedly committed the offence charged does not provide D with a 'defence' in itself.

Whether intoxication ends up mattering to liability depends first on whether it was voluntary or involuntary, and — for voluntary intoxication — on whether the offence charged requires 'specific intent' or only 'basic intent'. Voluntary intoxication can negate specific intent but never basic intent; involuntary intoxication, by contrast, is capable of negating the required fault element for any offence, since the report describes involuntary intoxication as founding a rule with no exceptions once it is shown to have actually prevented the defendant forming the necessary state of mind.

This same underlying question — did the defendant, despite being intoxicated, still form the intent or other mental state the offence requires — recurs throughout the criminal law wherever intoxication is raised, including in relation to automatism and to partial defences to murder such as loss of control and diminished responsibility, where CPS legal guidance confirms that self-induced intoxication is to be disregarded for the purposes of the loss of control partial defence.