Actus Reus

In criminal cases, the prosecution must prove that the defendant committed an actus reus and had mens rea at the same time.  Actus reus means a guilty act and mens rea means a guilty state of mind.

An actus reus consists of more than just an act. It also consists of whatever circumstances and consequences are required for the offence in question - in other words all the elements of an offence other than the mental element.  Crimes can be divided into two categories:
First, there are conduct crimes where the actus reus is the prohibited conduct itself. For example, the actus reus of the offence of dangerous driving is simply "driving a mechanically propelled vehicle on a road or other public place" (s2 Road Traffic Act 1988). No harm or consequence of that dangerous driving need be established.
The second type are known as result crimes where the actus reus of the offence requires proof that the conduct caused a prohibited result or consequence. For example, the actus reus of the offence of criminal damage is that property belonging to another must be destroyed or damaged (s1(1) Criminal Damage Act 1971).

The accused's conduct must be "voluntary" or "freely willed" if he is to incur liability. It may be involuntary for a variety of reasons:
Automatism occurs where the defendant performs a physical act but is unaware of what he is doing, or is not in control of his actions, because of some external factor, eg, R v Quick [1973] 3 All ER 347, where the defendant took an injection of insulin and had a blackout during which he assaulted the victim.
Sometimes people can respond to something with a spontaneous reflex action over which they have no control.  The classic example is that given in Hill v Baxter [1958] 1 All ER 193, of someone being stung by a swarm of bees while driving, and losing control of the car.
The conduct may be involuntary if it is physically forced by someone else, in which case there will be no actus reus, eg, Leicester v Pearson [1952] 2 All ER 71, where the defendant's car was forced onto a pedestrian crossing after being bumped by the driver behind.

One group of cases which cannot be discussed in terms of voluntary acts are often referred to as the "state of affairs" cases. These crimes are defined not in the sense of the defendant doing a positive act but consisting in the defendant "being found", "being in possession" or "being in charge" etc.  In cases all the prosecution needs to prove are the existence of the factual circumstances which constitute the crime - the existence of the state of affairs. See: R v Larsonneur (1993).

The general rule is that there can be no liability for failing to act, unless at the time of the failure to act the defendant was under a legal duty to take positive action.  The difference between positive acts and omissions was highlighted in the Airedale NHS Trust v Bland [1993] 1 All ER 821, where the House of Lords held that euthanasia by means of positive steps to end a patient's life, such as administering a drug to bring about his death, is unlawful.  However, withdrawing medical treatment, including artificial feeding, from an insensate patient with no hope of recovery when it was known that the result would be that the patient would soon die, is lawful if it was in the patient's best interests not to prolong his life.
A positive duty to act exists in the following circumstances:
Liability for failing to act will be imposed where the defendant can be shown to have been under a statutory duty to take positive action.  A leading example of such a case is provided by the Children and Young Persons Act 1933, which creates the offence of wilfully neglecting a child. Hence by simply failing to provide food for the child, or failing to obtain appropriate medical care, a parent could be held criminally liable for any harm that results.  Another example is the Road Traffic Act 1988 which creates the offences of failing to provide a specimen when required to do so and failing to give a correct name and address when required to do so.
Where a person is under a positive duty to act because of his obligations under a contract, his failure to perform the contractual duty in question can form the basis of criminal liability. See: R v Pittwood (1902) 19 TLR 37.

A person in a public office may be under a public duty to care for others.  See: R v Dytham [1979] 3 All ER 641.

There is a common law duty of care where there is a relationship of reliance between defendant and victim. Thus if someone voluntarily assumes responsibility for another person then they also assume the positive duty to act for the general welfare of that person and may be liable for omissions which prove fatal. See: R v Stone and Dobinson [1977] 2 All ER 341.

If the defendant accidentally commits an act that causes harm, and subsequently becomes aware of the danger he has created, there arises a duty to act reasonably to avert that danger. See: R v Miller [1983] 1 All ER 978.

When the definition of an actus reus requires the occurrence of certain consequences, the prosecution must prove that it was the defendant's conduct which caused that result to occur.  For example, in murder the prosecution must prove that the victim died; in section 18 of the offences Against the Person Act 1861 that the victim was wounded or caused grievous bodily harm; and in criminal damage that the property was destroyed or damaged.  There are two types of causation:
(a) Causation in Fact, for which the "But For" Test is used.  See: R v White [1910] 2 KB 124.
(b) Causation in Law, if there is a possible novus actus interveniens (new intervening act) then a test for legal causation is used.  There are various tests for this, eg:
  • The defendant was the "operating and substantial cause" test from Smith;
  • The defendant's act or omission "contributed significantly" from Pagett; and
  • There was "more than a slight or trifling link" from Kimsey.
Note that there are other tests but one is no more important than another.
The following incidents will not break the chain of causation in law:
Physical characteristics of the victim, eg, Hayward where the defendant shouted at and chased after his wife who then collapsed and died of a medical condition.  The defendant was guilty of manslaughter using the "thin skull" rule.  It did not matter that no one else would have had such a condition.
Refusal of medical treatment, eg, Blaue where the defendant stabbed a Jehovah's Witness who then refused a blood transfusion on religious grounds and died.  The defendant was guilty of manslaughter and the court held that the actions of the victim could not be described as unreasonable.  See also, Holland.
Natural consequences of D's actions, eg, Pagett who used a woman as a human shield and shot at the police.  The police fired back and the woman was killed in the crossfire.  It was held that the instinctive, reasonable actions of the police by way of self-defence did not break the chain of causation.
Reasonable attempt to escape, eg, Roberts where a woman jumped out of a car after the driver made sexual advances.  He was guilty of causing actual bodily harm as the victim's actions were a reasonably foreseeable consequence of what the defendant was doing.  The Court of Appeal stated that the chain of causation would only be broken by the victim doing something "daft".
The switching-off of a life support machine, eg, Malcherek & Steel, where the court held that the operating and substantial cause of death had been the original wounds inflicted by the defendant.
The victim committing suicide, eg, Dhaliwal where the defendant was charged with manslaughter and inflicting GBH following his wife's suicide.  Although there was evidence that he had physically and mentally abused her, the trial judge dismissed the case because the prosecution chose not to continue with manslaughter and there was insufficient evidence of psychiatric GBH.  The Court of Appeal stated obiter: "As to manslaughter, in summary, as a matter of law, the prosecution of a spouse, or partner, or indeed any other individual whose unlawful conduct causes recognisable psychiatric illness, such as, for example, post-traumatic stress disorder, or battered wife syndrome, or reactive depression, with resulting suicide, subject always to issues of causation, is not excluded from the ambit of this offence."
Negligent medical treatment, eg, Smith where the defendant stabbed the victim but the victim was dropped on the way to the medical hut, not treated immediately and eventually given bad treatment.  Despite this, the defendant was guilty of murder as he was the operating and substantial cause of death (loss of blood).
A Further Note on Negligent Medical Treatment:
There is the exceptional case of Jordan, where the defendant stabbed the victim but the wound was mainly healed at the time of death.  The victim was given a drug to which he was allergic and large amounts of liquid through a drip which caused pneumonia and lead to death.  This was described by experts as "palpably wrong".  The defendant was not guilty of murder as the stab wound was merely the setting within which another cause of death (pneumonia) operated.
If medical treatment results in complications, see:
Cheshire – the defendant shot the victim who was taken to hospital and died two months later.  The defendant was convicted of murder and appealed on the ground that the death had been caused by a rare complication resulting from the medical treatment the victim had received; and the doctors failing to realise its seriousness and reacting quickly enough.  The Court of Appeal upheld the murder conviction asserting that the rare complication was a direct consequence of the defendant's acts, which remained a significant cause of the victim's death.  Beldam LJ laid down the following test: "Even though negligence in the treatment of the victim was the immediate cause of his death, the jury should not regard it as excluding the responsibility of the accused unless the negligent treatment was so independent of his acts, and in itself so potent in causing death, that they regard the contribution made by his acts as insignificant."