13. Defences I: incapacity and negating the elements of the offence

Abstract

Without assuming prior legal knowledge, books in the Directions series introduce and guide readers through key points of law and legal debate. Questions, diagrams, and exercises help readers to engage fully with each subject and check their understanding as they progress. This chapter discusses the following general defences: infancy, insanity, automatism, intoxication (involuntary and voluntary), and mistake. Children under 10 are conclusively presumed incapable of committing a criminal offence. Insanity (insane automatism) is concerned with the defendant’s mental condition at the time of the offence. Automatism is available where the defendant suffers a total loss of control or is unaware of what he is doing. Involuntary intoxication may be a defence to any offence if the defendant does not have the mens rea for that offence. Voluntary intoxication is no defence to a basic intent offence. A mistake as to civil law may negate the mens rea of an offence.