3.2 - Murder - common law liability
This lesson teaches murder as a common law fatal offence for AQA Paper 1 Criminal law. You will learn how to prove the actus reus, causation and mens rea in the correct order, how to use authority as a reasoning tool, and how to make controlled AO2 and AO3 points without drifting into separate partial-defence questions.
The Offence And The Exam Issue
Murder is a common law offence, so its definition comes from the judges rather than from an Act of Parliament.
Murder
The unlawful killing of a reasonable creature in being under the King's peace, with malice aforethought: an intention to kill or an intention to cause serious injury.
The offence has to be built in this order:
| Stage | What must be proved | Usual authority or source role | Consequence if missing |
|---|---|---|---|
| Actus reus | D unlawfully caused the death of a human being under the King's peace | Common law definition; actus reus principles | No murder, though another offence may be possible |
| Causation | D's conduct was a factual and legal cause of death | Cases on factual and legal causation | No liability for that death |
| Mens rea | D intended death or serious injury | Cases on express and implied malice, direct and oblique intention | No murder; consider manslaughter only if another route applies |
AQA exam reports repeatedly reward students who answer the question asked. If the question asks about murder, prove murder first. Do not start with loss of control, diminished responsibility, insanity or self-defence unless the question requires them. Those issues may reduce or avoid liability, but they are not substitutes for proving the prima facie offence.
The key exam discipline is selectivity. If the facts obviously involve an adult victim killed during an ordinary civilian incident, say "human being under the King's peace" briefly and spend the real time on causation and mens rea. If the facts involve an unborn child, life support, refusal of treatment, a mistaken target, or a borderline intention, then that feature becomes legally material.
Actus Reus: Unlawful Killing
The actus reus of murder is an unlawful killing. Break that phrase into operational elements before applying it:
| Element | Meaning | Common confusion |
|---|---|---|
| Killing | V must be dead, and D's conduct must be linked to that death | Do not assume causation just because D injured V |
| Human being | V must be a person in law: traditionally described as a reasonable creature in being | An unborn child is not a murder victim while still in utero; if born alive and later dies from prenatal injuries, analyse the facts carefully rather than assuming murder |
| Under the King's peace | The victim must be protected by ordinary criminal law | This is usually only a brief point in AQA scenarios |
| Unlawful | The killing is not legally justified; complete excuses are considered separately | Do not confuse this with partial defences, which are considered after murder is otherwise made out |
The actus reus can be committed by an act, such as stabbing, shooting, striking or driving at V. It can also be committed by an omission where D is under a legal duty to act and fails to do so. For AQA, the omission point matters only where the facts show a recognised duty situation, such as a duty arising from relationship, contract, voluntary assumption of care, creation of danger, or statute. Even then, mens rea still has to be proved; omission liability does not remove the need for intention.
Cases should be used as legal tools. Attorney-General's Reference (No 3 of 1994) is useful where the facts involve an unborn child: the legal point for this lesson is that a foetus is not a "reasonable creature in being" for murder. R v Malcherek is useful where doctors switch off life support: the legal point is that medical confirmation of death or ending futile treatment does not automatically break the link between D's earlier injury and V's death.
In a scenario, do not write a long history of murder. Write the actus reus as a short proof sequence:
- Identify the death.
- Identify the conduct or omission.
- Check V is a human being protected by criminal law.
- State that the killing is unlawful unless a complete defence is available.
- Move quickly to causation.
Causation: Linking D To Death
Causation connects D's conduct to V's death. It is part of the actus reus, but it deserves separate treatment because fatal offence questions often turn on whether the chain has been broken.
Use two stages.
| Stage | Test | Authority tool | How to apply |
|---|---|---|---|
| Factual causation | But for D's conduct, would V have died when and as they did? | R v White illustrates that D is not the factual cause if V would have died anyway | Ask the counterfactual directly; do not replace it with moral blame |
| Legal causation | Was D's conduct an operating and substantial cause, more than minimal? | R v Smith supports the "operating and substantial" approach | D need not be the only cause; the question is whether D's contribution remains legally significant |
Intervening acts are the main difficulty. An intervening act breaks the chain only if it makes D's contribution no longer legally significant. The threshold is demanding:
| Intervening issue | Legal point | Authority tool | Application clue |
|---|---|---|---|
| Medical treatment | Poor treatment rarely breaks the chain; it must be very independent and very potent before D's act is displaced | R v Cheshire; R v Jordan as the exceptional contrast | Ask whether the original wound is still a significant cause |
| Victim's condition or belief | D takes V as found | R v Blaue | A refusal of treatment or unusual vulnerability usually does not help D |
| Victim's escape or reaction | A reasonably foreseeable reaction normally keeps the chain intact | R v Roberts; R v Williams for an unreasonable reaction contrast | Ask whether V's response was within the range of expected reactions to D's threat or attack |
| Third party act | The stronger and more independent the third party act, the more likely it may break the chain | R v Pagett shows using another person as a shield can still leave D causally responsible | Identify whether the third party act was free, deliberate and overwhelming |
The legal consequence is binary for murder: if causation fails, D is not guilty of murdering V. But the reasoning is rarely binary. Strong AO2 explains why a possible break is weak or strong. For example, "V died in hospital" is not enough; "the hospital administered treatment so independent of D's wound that the wound was no longer significant" would be the kind of argument needed.
Mens Rea: Malice Aforethought
The mens rea of murder is malice aforethought. The phrase sounds historical, but the exam rule is modern and precise: D must intend to kill or intend to cause serious injury. Recklessness is not enough for murder.
There are two routes.
| Route | Meaning | Authority tool | Application facts |
|---|---|---|---|
| Express malice | Intention to kill | R v Mohan is used for direct intention: D's aim or purpose is to bring about the result | Statements, planning, targeting vital parts, repeated force, weapon choice |
| Implied malice | Intention to cause serious injury or GBH | R v Vickers and R v Cunningham (1982) support that intention to cause GBH is enough for murder | Heavy blows, stabbing, shooting, use of dangerous weapons, attack to head or torso |
Do not confuse Cunningham (1982) on murder with Cunningham (1957) on recklessness. Murder does not require subjective recklessness; it requires intention to kill or intention to cause serious injury.
Intention can be direct or oblique:
| Type of intention | Test | Consequence |
|---|---|---|
| Direct intention | Death or serious injury was D's aim or purpose | The jury can find the mens rea of murder if the actus reus and causation are also proved |
| Oblique intention | Death or serious injury was a virtual certainty from D's act, and D appreciated that virtual certainty | Under R v Woollin, this is evidence from which a jury may find intention |
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