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Actus reus, mens rea and participation — SQE1 Criminal question

A worked single-best-answer question on actus reus, mens rea and participation, with why each wrong option is wrong — the way SQE1 traps candidates.

Actus reus, mens rea and participation

During an argument outside a nightclub, Aaron stabbed Ben in the abdomen. Ben was taken to hospital, where he was given a drug to which he was known to be allergic, owing to a negligent mistake by a junior doctor. Ben died two days later. Medical evidence shows that the stab wound remained serious and was still a significant cause of death, although the drug reaction contributed to it. Aaron is charged with murder.

Which of the following best describes whether Aaron caused Ben's death?

  1. AAaron did not cause Ben's death, because negligent medical treatment always breaks the chain of causation.
  2. BAaron did not cause Ben's death, because the stab wound was not the sole cause of death.
  3. CAaron caused Ben's death only if he foresaw that Ben might receive negligent treatment.
  4. DAaron caused Ben's death, because the stab wound remained an operating and significant cause and the treatment was not so independent and potent as to break the chain.
  5. EAaron caused Ben's death, because a defendant must take his victim as he finds him.
Show answer and reasoning
D is the best answer. The defendant's act need not be the sole cause of death; it is enough that it was an operating and significant cause (R v Smith). Negligent medical treatment breaks the chain only if it is so independent of the defendant's acts, and so potent in causing death, that the original injury becomes insignificant (R v Cheshire). The stab wound was still a significant cause, so causation is established.

Rule: Negligent medical treatment breaks the chain of causation only if it is so independent and potent that the defendant's act is no longer a significant cause of death.

  • A Medical negligence breaks the chain only in extreme cases where the original wound is no longer significant (R v Cheshire). (wrong rule)
  • B The defendant's act need only be a significant, more than minimal, cause, not the sole cause. (wrong rule)
  • C Causation is an objective question; foresight of the intervening treatment is not required. (wrong rule)
  • E The thin skull rule concerns the victim's own characteristics, such as a pre-existing condition, not a third party's negligent treatment. (right rule, wrong facts)

Source: R v Smith [1959] 2 QB 35; R v Cheshire [1991] 1 WLR 844

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