2.1.2 Actus Reus Lecture

Elements of an Offence

In order for an individual to be found liable for any offence, three elements must be satisfied.

  • There must be guilty conduct by the defendant (actus reus)
  • The defendant must have a guilty state of mind (mens rea)
  • There must be no valid defence

This chapter will examine the first element of liability, the actus reus.

The actus reus of a crime may be categories into one or multiple of three categories:

  • Conduct – The actus reus requires a certain conduct
  • Circumstantial – The act itself is not criminal, but the circumstance is
  • Result – The actus reus requires a result.

Section 1(1) of the Criminal Damage Act 1971 provides an excellent example of all three of the above:

A person who, without lawful excuse destroys or damages property belonging to another intending to destroy or damage any such property or being reckless as to whether any such property would be destroyed or damaged shall be guilty of an offence.

  • Conduct – some action that results in damage to property;
  • Circumstance – the property belongs to somebody other than the defendant;
  • Result – the property is damaged or destroyed.

This may be contrasted with Section 1 of the Sexual Offences Act 2003:

  1. A person (A) commits an offence if –
  1. he intentionally penetrates the vagina, anus or mouth of another person (B) with his penis,
  2. B does not consent to the penetration, and
  3. A does not reasonably believe that B consents.

In that offence, only a conduct actus reus is present – the penetration with the penis without the victim’s consent. It is therefore the conduct of the defendant that satisfies the actus reus, no particular result is necessary.

Liability for omissions

Usually, an actus reus requires an action. There are however, several circumstances where a duty to act is imposed and where omission satisfies the actus reus of an offence.

Duty arising from a special relationship:

  • Care or control of children – Section 1 of the Children and Young Persons Act 1933 – This makes it an offence for a parent or any other person over the age of 16 years who has responsibility for a child under the age of 16 years to wilfully neglect the child
  • Assumption of Care for Another – The Children and Young Persons Act 1933 does not extend beyond those of the age of 16 years and therefore no direct obligation is placed on a parent to care for an independent 18-year-old child (R v Shepherd(1862) 9 Cox CC 123). However, two important judgments highlight the approach that is taken in respect of where care is assumed over an individual who is over the age of 16.

- R v Instan [1893] 1 QB 450 – The defendant cared for his aunt who was unable to feed herself or seek medical help. The defendant did not feed or seek any medical help for his aunt, despite living with her. The defendant’s assumption of care and blood relationship made him negligently liable for her death.

- R v Stone and Dobinson [1977] QB 354 – The above potential requirement of a blood relationship was removed in this case. The assumption of care by one of the defendants before the omission to care for the victim rendered the defendant guilty.

  • Contractual duties – R v Pittwood(1902) 19 TLR 37 – A person may be found criminally liable if they fail to comply with a contractual duty they have to another. In this case, the defendant was employed to operate the gates at a level crossing. He failed to close the gates when a train was approaching and a cart was struck by the train killing one of the carters. Pittwood was convicted of manslaughter. A contractual duty to do a particular thing, imposes a duty to do that thing in order to prevent harm to particular individuals.

Duty Arising out of a Danger of One’s Own Making: R v Miller [1983] 2 AC 161 - Where a person creates a dangerous situation, they may be placed under an obligation to take reasonable steps to remove the danger and therefore, may be criminally liable if they do not do so.

In R v Evans [2009] EWCA Crim 650, it was held that the approach in Miller could be taken a stage further where it was held that an individual could be liable in gross negligence manslaughter when they unlawfully supply a victim with a dangerous drug and then fail to obtain help for the victim when it becomes clear that the victim has fallen ill as a result of taking the drug.

Statutory Duty: Section 170 of the Road Traffic Act 1988, for example.

Medical Treatment: In ordinary circumstances, as was set out above, doctors are required to act in order to provide their patients with proper medical treatment. This requirement is removed where a patient with the required level of capacity specifically refuses treatment. In certain limited circumstances, the court will allow doctors to remove medical treatment where it is considered to be in the patient’s best interests, such as in Airedale National Health Service Trust v Bland [1993] AC 789.

Offences where Omission Never Gives Rise to Liability: Offences that specifically require a positive act can clearly not be committed by omission, for example, assault of theft.


  • The actus reus must be voluntary by the defendant
  • Automatism (covered in chapter 10)


In order for a defendant to be found liable for an offence, it is necessary that the defendant’s actions cause the harm. Causation falls into two categories: factual and legal – both must be satisfied.

Factual Causation

The relevant test to apply is the ‘but for’ test. The question that is asked is whether ‘but for’ the defendant’s actions, the harm to the victim would have occurred – In R v White [1901] 2 KB 124, the defendant laced the victim’s drink with cyanide, the mother did not drink much of the drink, and died coincidentally that night, therefore, the defendant was not the factual cause of death.

Multiple causes: A defendant may be guilty of causing something to happen if his conduct was not the only cause of it, even if his conduct alone was not sufficient to cause the harm to occur (R v Warburton [2006] EWCA Crim 627).  It was suggested in R v Hennigan [1971] 3 All ER 133, that a 20% contribution would be sufficient and in R v Notman [1994] Crim LR 518, that anything above a minimal contribution would suffice.

Legal Causation

Legal causation has the effect of limiting this potentially broad liability, as factual causation is very easy to prove. There are three specific elements that must be satisfied for legal causation

  • The cause was substantial (more than slight or trifling – R v Kimsey [1996] Crim LR 35
  • Defendant must be blameworthy to some extent – R v Dalloway (1847) 2 Cox CC 273
  • Defendant’s actions must be operating on the victim at the time that liability arises – R v Pagett (1983) 76 CR App R 279

Novus Actus Interveniens

These elements may not be present and the defendant may avoid liability even if found to have factually caused the victim’s harm in two circumstances. These can be categorised as:

  • some act of another person that intervenes between the defendant’s conduct and the end result;
  • or some event which occurs between the defendant’s conduct and the end result.

These circumstances are often described collectively as a novus actus interveniens.

Act of a third party: Only if the act of a third party renders the defendant’s actions non-operable on the victim will this break the chain of causation

Where both parties’ actions can be considered collectively to result in the harm suffered by the victim, both potential defendants are considered to have caused the harm. It does not matter that one defendant’s actions are the main cause of the harm and one defendant’s are not. All that is necessary, is that the defendant can be considered to a contributed significantly to the harm (R v Pagett (1983) 76 Cr App R 279).

Causation will not be broken unless the actions of the third party are free, deliberate and informed - R v Pagett,

Medical Intervention

In R v Jordan(1956) 40 Cr App R 152, the defendant was admitted to hospital with stab wounds. When the victim died 8 days later, his wounds had largely healed and it was held that it was medical treatment subsequent to the healing of the wounds that caused the death, rather than the wounds themselves. The wounds were not an operating and substantial cause of the death.

In R v Smith [1959] 2 QB 35 on broadly similar facts to Jordan the defendant was unable to rely on the intervening medical acts, even though these were found to be extremely poor, because in this context, the victim’s wounds were still operating and substantial at the time of the death.

The threshold was narrowed in R v Cheshire [1991] 1 WLR 844, where it was held that the chain of causation will be broken by poor medical treatment if the treatment is ‘… so independent of [the defendant’s] acts, and in itself so potent in causing death, that [the court] regard[s] the contribution made by [the defendant’s] acts as insignificant’.

The effect of medical treatment on causation must be considered very carefully and the remaining effect of the initial wound must be looked at in detail. It is only safe to say that the chain of causation will only be broken where the original injury is insignificant in the face of the poor medical treatment. If any remnant of the original injury remains, it is unlikely that even very poor medical treatment will mean that a defendant is not found to have caused a victim’s harm.

Acts of the victim

The general position in respect of acts of victims is that an individual should be held responsible for acts that they undertake freely.

In R v Kennedy(No 2)[2007] UKHL 38, for example, it was held that a person who provided another will a syringe containing heroin could not be held liable when the victim injected themselves with it. This was because the act of injection was carried out freely and therefore broke the chain of causation from the act of providing the drug.

This approach does not apply where the acts of a victim cannot be considered to have been carried out freely. The most common situation where this principle is applied is where a victim is attempting to escape from a defendant. In this case, it is a question of whether the actions of the defendant were reasonable in the circumstances - R v Williams and Davies [1992] 1 WLR 380

Eggshell Skull Rule

This rule requires the defendant ‘must take their victim as they find them’ – a victim’s particularly weakness to something will be irrelevant and will not break the chain of causation.

In R v Hayward(1908) 21 Cox CC 692, the defendant was found liable for his wife’s death from a pre-existing heart condition when he threatened her causing her to suffer a heart attack. The approach was taken further in R v Blaue [1975] 1 WLR 1411 where the defendant stabbed a woman who was a Jehovah’s Witness. As a result of her religious beliefs the victim refused a blood transfusion, which would have saved her life. The defendant was, however, found liable for her death on the basis that the religious beliefs of the victim could not be found to interfere with causation.

Acts of God

An act of God is defined as freak natural phenomenon, so unpredictable that it ought to excuse the defendant of all liability (Southern Water Authority v Pegrum [1989] Crim LR 442). Such an act must be completely unpredictable. Such an act will break the chain of causation.

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