Crime Components: Actus Reus & Mens Rea

Introduction

Most criminal offences require proof of two elements: the actus reus (the conduct element) and the mens rea (the mental element). For result crimes, the prosecution must also prove that the defendant’s conduct caused the prohibited result. Broadly, the actus reus must be voluntary, the required mens rea must relate to that conduct, and there must be a factual and legal link between the conduct and any harm. Some offences are exceptions, operating without mens rea (strict liability), but the courts presume mental fault is required unless Parliament clearly says otherwise.

This guide sets out the key rules, leading authorities, and practical steps to apply in problem questions and practice.

What You’ll Learn

• What actus reus covers: acts, omissions, states of affairs, and voluntariness
• When an omission can satisfy the actus reus due to a legal duty to act
• Common duties: contractual, special relationships, voluntary assumption, official position, and creation of danger
• How mens rea varies by offence: intention (direct and oblique), recklessness, and negligence
• When mens rea is not required: strict liability and the presumption in favour of fault
• Causation: factual and legal tests, intervening acts, and the thin skull rule
• Coincidence and transferred malice: making mens rea line up with the act
• Practical steps to analyse offences, plus frequent pitfalls to avoid

Core Concepts

Actus Reus: Conduct, Circumstances, and Results

• Meaning: The external element of an offence. This may be conduct alone (e.g., driving), conduct plus circumstances (e.g., sexual activity without consent), or conduct causing a result (e.g., death in homicide).
• Voluntariness: Liability generally requires a voluntary act. Involuntary conduct (e.g., reflex actions or automatism) cannot form the actus reus. See Hill v Baxter [1958] 1 QB 277 (driver attacked by a swarm of bees as an example of involuntariness).
• States of affairs: Some offences criminalise being in a particular situation rather than doing a specific act. In Larsonneur [1933] 24 Cr App R 74, the defendant was found “found in” the UK contrary to immigration conditions, even though she had been brought back involuntarily. In Winzar v Chief Constable of Kent (1983) 77 Cr App R 334, the defendant was “found drunk on a highway” after being moved there by police.

Note: Possession offences typically require control and awareness. Where Parliament intends strict liability, it must be clear.

Omissions and Duties to Act

There is no general duty to rescue. An omission will only suffice where a recognised duty exists:

• Statutory duties: e.g., duties under the Road Traffic Act.
• Contractual duty: R v Pittwood (1902) 19 TLR 37 (gatekeeper failed to shut a crossing gate).
• Special relationship: R v Gibbins and Proctor (1918) 13 Cr App R 134 (parental duty to child).
• Voluntary assumption of care: R v Stone and Dobinson [1977] QB 354 (caring for a vulnerable relative).
• Duty arising from office: R v Dytham [1979] 1 QB 722 (police officer wilfully neglecting duty).
• Creating a dangerous situation: R v Miller [1983] 2 AC 161 (duty to act once you create a danger, here failing to deal with a smouldering mattress).

The failure to discharge a duty, where it results in the prohibited harm or risk, can satisfy the actus reus.

Mens Rea: Intention, Recklessness, Negligence

• Intention

  • Direct intention: The result is the defendant’s aim or purpose.
  • Oblique intention: The jury may find intention where the defendant foresaw the result (e.g., death or serious injury) as a virtual certainty and appreciated that to be so. See R v Woollin [1999] 1 AC 82. The direction allows, but does not compel, a finding of intention.

• Recklessness

  • The modern approach is subjective. Under R v G and R [2003] UKHL 50, a person is reckless if they are aware of a risk that exists or will exist, or that a result will occur, and, in the circumstances known to them, it is unreasonable to take that risk. Earlier, R v Cunningham [1957] 2 QB 396 endorsed a similar subjective test.

• Negligence

  • Ordinary negligence rarely suffices for criminal liability unless specified. For gross negligence manslaughter, R v Adomako [1995] 1 AC 171 requires a duty of care, breach, causation, and a risk of death, where the breach is so bad it is judged gross by the jury.

Strict Liability

Some offences require only proof of the actus reus.

• Presumption of mens rea: Strongly favoured by the courts. Sweet v Parsley [1970] AC 132 held that if an offence is truly criminal and the statute is silent, mens rea is usually required.
• When the presumption may be displaced: Consider the “Gammon factors” from Gammon (Hong Kong) Ltd v AG of Hong Kong [1985] AC 1, including the wording of the statute, the regulatory nature of the offence, the seriousness of penalties, and the public interest in enforcement.
• Example: Harrow LBC v Shah [2000] 1 WLR 83 (sale of a lottery ticket to a minor was strict liability despite checks).

Coincidence and Transferred Malice

• Coincidence (concurrence): The mens rea must coincide with the actus reus. The courts sometimes treat events as a continuing act or a single transaction to achieve fairness:

  • Continuing act: Fagan v MPC [1969] 1 QB 439 (car left on an officer’s foot; mens rea formed while the act continued).
  • Single transaction: Thabo Meli v R [1954] 1 WLR 228 (series of acts viewed as one transaction).

• Transferred malice: Mens rea can transfer from the intended victim to the actual victim if the offence is of the same type. See R v Latimer (1886) 17 QBD 359. It will not transfer between different offences, e.g., from an offence against the person to criminal damage: R v Pembliton (1874) LR 2 CCR 119.

Causation: Factual and Legal

For result crimes, the prosecution must prove both:

• Factual causation: The “but for” test. Would the result have occurred but for the defendant’s conduct? See R v White [1910] 2 KB 124 (poisoning case where the victim died of a heart attack anyway; the defendant was not the factual cause of death).

• Legal causation: The defendant’s conduct must be a more than minimal cause and remain operative at the time of the result. Intervening acts can break the chain:

  • Medical treatment: Only exceptional negligence breaks the chain. R v Jordan (1956) 40 Cr App R 152 (palpably wrong treatment) broke the chain; R v Smith [1959] 2 QB 35 and R v Cheshire [1991] 1 WLR 844 did not.
  • Acts of third parties: Will break the chain if free, deliberate, and informed, and not reasonably foreseeable. In R v Pagett (1983) 76 Cr App R 279, police returning fire did not break the chain because their actions were a foreseeable response to the defendant’s conduct.
  • Victim’s own act: R v Roberts (1972) 56 Cr App R 95 (victim’s reaction must be reasonably foreseeable); R v Williams and Davis [1992] Crim LR 198 refined the test.
  • Thin skull rule: Take your victim as you find them. R v Blaue [1975] 1 WLR 1411 (refusal of a blood transfusion on religious grounds did not break the chain).

Key Examples or Case Studies

R v Woollin [1999] 1 AC 82

• Context: Oblique intention for murder.
• Key point: A jury may find intention where death or serious injury was a virtual certainty from the defendant’s act and the defendant appreciated that.
• Application: Use when a defendant denies direct aim but foresaw a virtually certain outcome.

R v Miller [1983] 2 AC 161

• Context: Omissions where the defendant creates a danger.
• Key point: Once you create a risk (e.g., a smouldering mattress), you come under a duty to take reasonable steps to avert it; failure can complete the actus reus.
• Application: Analyse “creation of danger” scenarios rather than searching for a pre-existing duty.

Fagan v MPC [1969] 1 QB 439

• Context: Coincidence of actus reus and mens rea.
• Key point: A continuing act allows mens rea formed after the original act to coincide with the ongoing actus reus.
• Application: Where timing is tricky, consider continuing acts or a single transaction approach.

R v Pagett (1983) 76 Cr App R 279

• Context: Causation and third-party acts.
• Key point: A foreseeable response by third parties (police returning fire) will not break the chain of causation; the defendant remains a legal cause.
• Application: Use when intervening acts are reactions to the defendant’s conduct.

Davidge v Bennett [1984] Crim LR 297

• Context: Theft where money is given for a specific purpose.
• Key point: Spending flatmates’ bill money on gifts was an appropriation with intention to permanently deprive; s 5(3) Theft Act 1968 treats property given for a specific purpose as “belonging to another”.
• Application: Shows how actus reus (appropriation) and mens rea (intention to permanently deprive) can be inferred from purpose and use.

Practical Applications

• Read the statute first

  • Identify the conduct, circumstance, and result elements.
  • Check if the offence specifies intention, recklessness, knowledge, or negligence.

• Test actus reus methodically

  • Was the conduct voluntary? Consider automatism if relevant.
  • Is the allegation an omission? Identify a recognised duty: contract, relationship, assumption of care, official duty, or creation of danger.
  • For possession or state-of-affairs offences, confirm control and any required awareness.

• Match mens rea to each element

  • Intention: direct or oblique (Woollin).
  • Recklessness: did the defendant actually foresee the risk and unreasonably take it? (R v G and R).
  • Negligence: only where the offence allows it, or for gross negligence manslaughter (Adomako).

• Check coincidence and transferred malice

  • If timing is awkward, consider continuing acts (Fagan) or single transaction (Thabo Meli).
  • If the wrong person was harmed, ask whether transferred malice applies (Latimer; not for different offences, per Pembliton).

• Prove causation clearly for result crimes

  • Factual causation: but for the conduct, would the result have happened? (White).
  • Legal causation: was the conduct a more than minimal, operative cause? Examine medical treatment (Smith/Cheshire/Jordan), victim reactions (Roberts, Williams and Davis), third-party acts (Pagett), and thin skull (Blaue).

• Consider strict liability

  • If the statute is silent on mens rea, apply the Sweet v Parsley presumption.
  • Use the Gammon factors to decide whether Parliament likely intended strict liability.

• Always screen for potential defences

  • Self-defence, duress, insanity, automatism, intoxication, and mistake may affect liability even where the elements are present.

• Present a clean structure in answers and advice

  • Element by element: actus reus, mens rea, coincidence, causation, then defences.
  • Cite one or two leading authorities per point to keep the analysis sharp.

Summary Checklist

• Identify all actus reus components: conduct, circumstances, and any result
• Confirm voluntariness or a recognised omission-based duty
• Pin down the required mens rea from the statute or case law
• Apply the correct test for intention (Woollin) or recklessness (R v G and R)
• Use coincidence tools where timing is problematic (Fagan; Thabo Meli)
• Run both factual and legal causation, including thin skull and intervening acts
• Consider whether the offence is strict liability (Sweet v Parsley; Gammon)
• Check for defences that may negate or reduce liability
• Support each step with a concise authority

Quick Reference