3.2 - Actus reus, omissions and causation

The Actus Reus Map

Actus reus is often translated as the "guilty act", but that phrase is too narrow for AQA.

A strong answer first identifies which type of element is actually in issue.

The specification separates actus reus into conduct, acts and omissions, state of affairs, voluntariness, causation and consequences. That order matters. If the offence is a result crime, you must prove both the external behaviour and the causal link to the prohibited consequence. If the issue is an omission, you must first find a legal duty. If the issue is voluntariness, you must ask whether the conduct was really controlled by D.

Common confusion: actus reus is not the same as "everything except mens rea". Some actus reus elements are physical acts, but others are surrounding circumstances or consequences. Also, proving actus reus does not normally prove guilt by itself; the relevant mens rea or other fault element must still be considered unless the offence imposes strict liability as to that element.

Conduct And Voluntariness

For ordinary conduct offences, D's conduct must be voluntary. This does not mean D must want the result; it means D must have control over the bodily movement that forms the actus reus. A person who is physically pushed into V, has a genuine reflex movement, or acts while completely deprived of control may not have performed a voluntary act.

The authority AQA commonly accepts for this point is Hill v Baxter. The case is used for the legal principle that criminal liability normally requires voluntary conduct. It is not enough for D to say, after the event, "I did not mean it"; the issue is whether D lacked control of the relevant movement. Broome v Perkins shows the boundary: a diabetic driver in a hypoglycaemic state still had some control over the car, so the conduct could be treated as voluntary.

Use this sequence in a scenario:

1. Identify the exact movement alleged to be the actus reus.
2. Ask whether D had physical control over that movement.
3. If D had no control, explain why the actus reus is not satisfied.
4. If D had some control, treat the conduct as voluntary and move to mens rea or any separate defence.

Voluntariness is separate from intention. If D swings an arm during an argument and hits V, the movement may be voluntary even if D did not intend serious injury. If D is shoved from behind and falls into V, the contact may be harmful, but the movement is not D's voluntary act.

Omissions And Legal Duties

The starting point is that criminal law usually punishes acts, not mere failures to act. An omission can satisfy actus reus only where the law recognises a duty to act and the offence can be committed by failing to act. AQA materials expressly recognise that an Act of Parliament can create liability for an omission, and examiner reports also expect students to understand common law duty categories.

Use this five-stage omissions method:

1. Is D being blamed for a failure to act rather than a positive act?
2. Is there a legal duty, not just a moral expectation?
3. Did D breach that duty by failing to do what was required?
4. If the offence requires a consequence, did the omission cause it?
5. Is the required mens rea or fault element present?

The recognised duty categories are best learned through the legal job done by each authority.

A duty does not automatically create liability for every offence. Murder, for example, can be committed by omission where a legal duty exists, the omission causes death, and the mens rea for murder is proved. By contrast, some offences are worded or understood as requiring a positive act. Always connect the duty to the offence being charged.

Common confusion: "D was a friend" or "D behaved badly" is not enough. The duty must be legally recognised. Another common error is to find a duty but forget causation: if V would have died at the same time even with reasonable action, the omission has not caused the consequence.

State Of Affairs And Consequences

State of affairs offences are unusual because liability is based on D being in a prohibited situation, rather than on proving that D voluntarily caused that situation. They matter because the AQA specification expressly includes "state of affairs" within actus reus, and because they test the boundary between external liability and fault.

Two mainstream examples show the idea. In R v Larsonneur, D was convicted after being found in the United Kingdom in circumstances prohibited by immigration law, even though she had been brought back from Ireland against her wishes. In Winzar v Chief Constable of Kent, D was treated as liable for being found drunk on a highway after police removed him from a hospital to that location. Use these cases carefully: their purpose is to illustrate state of affairs liability, not to suggest that every offence ignores voluntariness or fault.

State of affairs must be kept separate from consequence crimes.