House of Lords · Unanimous: Lords Diplock, Fraser of Tullybelton, Roskill, Brandon of Oakbrook and Brightman. Lord Diplock gave the only reasoned speech.
Facts
The appellant, a squatter, fell asleep on a mattress while smoking a cigarette. He awoke to find the mattress smouldering but did nothing to put out the fire, simply moving to another room and going back to sleep. The fire spread and caused significant damage to the house. He was charged with arson under the Criminal Damage Act 1971.
History
The appellant was convicted at trial. The Court of Appeal dismissed his appeal. He appealed to the House of Lords.
Issue
Whether a person who inadvertently creates a dangerous situation can be liable for a crime requiring a positive act (arson) by virtue of an omission to take reasonable steps to counteract the danger.
Held
Appeal dismissed; conviction upheld.
Ratio
- Where a person inadvertently creates a dangerous situation, he is under a duty to take reasonable steps to avert the danger; a breach of that duty by omission can constitute the actus reus of a crime such as arson, provided the offence can be committed by an omission.
The judgments
Lord Diplock (lead)
Held that a person who inadvertently starts a fire and then becomes aware of it is under a responsibility to take reasonable steps to prevent or limit the damage, and that failing to do so with the mens rea for criminal damage is enough for arson. He preferred this duty or responsibility analysis to the Court of Appeal's treatment of the whole course of conduct as one continuing act, as simpler to explain to a jury, while accepting that both led to the same result. The other Law Lords concurred.
Key reasoning
- The actus reus of arson under the Criminal Damage Act 1971 does not require a positive act; it can be satisfied by an omission where a duty to act exists.
- A duty to act arises when the defendant creates a dangerous situation, even inadvertently.
- Lord Diplock preferred to rest liability on the duty arising from responsibility for the danger, not on the Court of Appeal's view of the conduct as a single continuing act; the mens rea must exist when the defendant becomes aware of the danger he has created and fails to act.
Where it fits in the module
This case is central to Topic 1 (Basic Principles of Criminal Law) as it illustrates the actus reus of omissions, the circumstances in which a duty to act arises, and the coincidence of actus reus and mens rea. It contrasts with cases like R v Larsonneur (strict liability for being in a place) and R v Stone and Dobinson (duty arising from assumption of care). It also relates to the debate on whether omissions should be criminalised and the limits of the 'social responsibility' theory.
Criticisms
- Even on Lord Diplock's duty analysis, the line between acts and omissions is hard to hold: a person who inadvertently creates a danger is treated as liable for failing to undo it, with no clear limit on how far the duty extends.
- It imposes a duty on a person who may not have the capacity or opportunity to avert the danger effectively.
- The principle could be extended too broadly, potentially criminalising mere inaction in a wide range of situations.
- The mens rea requirement (recklessness as to damage) was satisfied by the appellant's awareness of the risk, but the case leaves open the precise mental element required for omission liability.
Written with AI (nvidia/nemotron-3-ultra-550b-a55b) on 1 November 2026, reviewed for errors by a second model (claude-sonnet-5.5 (Claude Code reviewer)). Read the case itself at [1983] 2 AC 161, [1983] Crim LR 466. Spotted an error? Tell us.