Actus reus is latin for 'the guilty act'. This is only liable for positive acts, generally not omissions.
All acts must be voluntary (a concious, deliberate movement of the muscles), the defendant must be consciously in control of his actions. R V Burgess, Hill V Baxter.
There are 3 different types of offence with different ways of achieving the actus reus:
1) conduct crimes - where the conduct of the victim is the actus reus (e.g lying under oath, perjury)
2) result of consequence crimes - requires defendant's conduct to result in something illegal (e.g in murder the result of d's unlawful act or omission is the death of another human)
3) state of affair crimes - rare, but means that d will be guilty of an offence by being in a particular place when the state of affairs is prohibited. R V Larsonneur.
The actus reus should be a postive act, except from where there is an omission.
An omission is a failure to act in given circumstances. There are 6 omissions.
1) Where a special relationship exists between the parties. R V Gibbins and Proctor.
2) Where the defendant has voluntarily accepted responsibility for the other person. R V Stone and Dobinson.
3) Where the defendant has caused a dangerous situation and has failed to put it right. R V Miller.
4) Where there is a contractual duty. R V Pittwood.
5) Where the defendant holds a public office. R V Dytham.
6) Where the duty to act is imposed by a statute. Road Traffic Act 1988.
It must always be proved by the prosecution that the defendant cause the result of the offence.
The defendant will only be guilty where their acts are both a factual and legal cause of the results constituting the offence.
There are two types of causation that must be established; factual causation and legal causation.
Factual causation is established by the 'but for' test. 'But for' the defendant's actions would the harm have occurred? If the answer is no, factual causation is satisfied. If the answer is yes, there is no factual causation and the defendant cannot be held liable. R V White, R V Pagett.
Legal causation is more difficult to prove in problem questions, but in real life is not an issue. If A stabs B and B dies then it is clear A caused B's death. However on rare occasions an intervening act may occur. If A stabs B and B is taken to a hospital and the surgeon makes a mistake during a procedure and B dies has A caused B's death or the surgeon? Judicial precedent is used to determine this.
Has the defendant received palpably bad medical treatment? The original injury must be the 'operating and significant cause' of harm. In cases involving medical intervention the courts are reluctant to allow this as a break in causation. R V Jordan - exceptional circumstance. R V Smith - defendant's action was the operating and significant cause. R V Cheshire - changed the word substantial to significant as it is less difficult to prove.
Has an intervening act occurred? Also known as novus actus interveniens. The intervening act which causes the death or serious injury may seem to be completely independent from the original wound. R V Pagett - Defendant found to be cause as the response of the third party was reasonably foreseeable. R V Malcherek - the effect of the life support machine was merely to hold the effect of the injuries in suspension.
Legal Causation continued
Has the harm increased due to a pre-existing condition or feature of the victim?
R V Blaue - you must take your victim as you find them. Also known as the thin skull rule.
Has the harm been made worse by the victim's own conduct?
R V Roberts - if the conduct of the victim is reasonably foreseeable then there will be no break in causation.
R V Williams - the conduct of the victim was not reasonably foreseeable. However it should be kept in mind that the victim may act without thought or deliberation in certain situations.