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Involuntary Manslaughter: Unlawful Act

Study Note | A Level

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Involuntary manslaughter is an unlawful killing where a defendant does not have the intention to kill or cause serious bodily harm. The maximum sentence for involuntary manslaughter is life but the judge has discretion in sentencing.

Unlawful act manslaughter is also referred to as constructive manslaughter, as liability for a death is constructed from the facts.

Actus reus

There are three elements required for unlawful act manslaughter. The defendant must commit an unlawful act, the act must be dangerous and cause the death.

  • Unlawful act


    It must be a criminal offence as a civil wrong (tort) is not enough.

    Franklin (1883)

    Defendant took a box from another man's stall on Brighton pier and threw it into the sea. The box struck and killed the victim, who was swimming.

    It was held a civil wrong was not enough to create liability for unlawful act manslaughter.

    Lamb (1967)

    Defendant and victim were playing with a revolver. Both knew it was loaded but thought as the two bullets in the chamber were not opposite the hammer it would not fire. Defendant, as a joke, pointed the gun and pulled the trigger, killing the victim.

    It was held there was no assault (criminal act) because the victim shared in the joke and so felt no fear of violence. Defendant found not guilty of manslaughter.

    However, in many cases the unlawful act is an assault.


    An omission could not give rise to liability for unlawful act manslaughter.

    Lowe (1973)

    Defendant was found guilty of wilfully neglecting his baby son and manslaughter.

    Court of Appeal quashed his conviction as wilful neglect was based on an omission and so was insuffiecnet for a unlawful manslaughter conviction.

    Phillimore LJ: .. there is a clear distinction between an act of omission and an act of commission likely to cause harm. If I strike a child in a manner likely to cause harm it is right that if the child dies I may be charged with manslaughter. If, however, I omit to do something with the result that it suffers injury to health which results in death ... a charge of manslaughter should not be an inevitable consequence, even if the omission is deliberate....

  • Dangerous act

    Objective standard

    The test for whether an act is dangerous is an objective one.

    Church (1966)

    Lord Edmund-Davies: .. the unlawful act must be such as all sober and reasonable people would inevitably recognise must subject the other person to, at least, the risk of some harm resulting therefrom, albeit not serious harm....

    So there is only a requirement that a reasonable person would have foreseen the harm, not necessarily the defendant and the risk only needs to be some harm not serious harm.

    Unintended victim

    It does not matter if the victim was the person the unlawful act was aimed at.

    Larkin (1943)

    Defendant brandished a knife to threaten another. The victim, who was intoxicated, fell into the knife, which cut her throat and killed her.

    On appeal, defendant’s conviction for manslaughter was upheld, as he had committed assault against another and it was a dangerous act.

    Lord Humphries: ..Where the act which a person is engaged in performing is unlawful, then if at the same time it is a dangerous act, that is, an act which is likely to injure another person, and quite inadvertently he causes the death of that other person by that act, then he is guilty of manslaughter....

    Mitchell (1983)

    Defendant argued with an elderly man in a post office queue and pushed him. The man fell into an elderly woman, the victim, who died from her injuries.

    Defendant had committed assault on the man. Defendant had committed an unlawful act which was dangerous. Defendant convicted of manslaughter.

    Against property

    The unlawful act may be aimed at property.

    Goodfellow (1986)

    Defendant deliberately set fire to his council flat in order to be given an alternative. Three people died in the subsequent fire.

    Court of Appeal upheld the defendant’s conviction for manslaughter.

    Physical harm

    The risk of harm must be physical.

    Dawson (1985)

    Defendants attempted to rob a petrol station wearing masks and armed with pickaxe handle and a replica gun. Victim, the attendnant, raised the alarm and then suffered a heart attack which killed him. Victim suffered from a seroius heart condition.

    Defendants convictions were quashed on appeal. Victim’s heart condition should not have been considered by the jury, as explained by Justice Watkins an objective test: .. can only be undertaken upon the basis of the knowledge gained by a sober and reasonable man as though he were present at the scene of and watched the unlawful act being performed....

    Court of Appeal also held that a an emotional disturbance was insufficient to amount to harm.

    However, if a reasonable person would be aware of a victim’s frailty and increased risk of physical harm the defendant would be liable.

    Watson (1989)

    Defendant threw a brick through the victim’s window intending to steal property. The victim, a frail 87 year old man, heard the noise and went to investigate. Defendant verbally abused the victim and left. Victim died 90 minutes later.

    Court of Appeal quashed conviction for manslaughter on the basis of an issue with causation. However, the court noted a reasonable person would have realised the frailty of the victim and therefore it was a dangerous act.

  • Substantial cause of death

    The unlawful act must be the substantial cause of death. The general rules of causation apply to involuntary manslaughter.

    Chain of causation

    Corion Auguiste (2004)

    Defendant threw an air bomb firework during the rush hour in an enclosed bus station. Victim, an elderly lady, was knocked over in the panic. She struck her head and died .

    Defendant’s act was the direct and substantial cause of death. Defendant was convicted of unlawful act manslaughter.

    Novus actus interveniens

    Kennedy (2007)

    Defendant filled a syringe with heroin and gave it to the victim. Victim injected himself and died. Defendant was convicted of manslaughter.

    House of Lords overturned the defendant’s conviction. Stating the victim voluntarily injecting himself was an intervening act which broke the chain of causation .

    Multiple causes of death

    The unlawful and dangerous is not required to be the sole cause of death so long as it was not a trivial cause.

    Shohid (2003)

    Defendant was part of a group who attacked the victim and his friend at a railway station. The victim and his friend were forced to jump on the tracks, the friend managed to climb back onto the platform but the victim was prevented by others and was killed by a train.

    Court of Appeal held the original attack to be sufficiently serious to cause the death.

    Carey (2006)

    Defendants, three girls, started a fight with the victim. Victim suffered minor bruises but as she ran away she died from an inherent heart disease which was aggravated by the running. Defendants were convicted of unlawful act manslaughter based on affray.

    Defendants convictions were quashed on appeal. It was held the victim had been running to get home, not from a serious threat. The dangerous act was a single punch, which was not the cause of death and a reasonable person would not have foreseen more than trivial harm.

    Series of unlawful acts

    Attorney General’s Reference (no. 4 of 1980) (1982)

    Defendant pushed the victim down the stairs so she landed on her head. Defendant believed she was dead. He dragged her upstairs by a rope around her neck and cut her throat. Finally he chopped up and disposed of the body. Defendant had committed a series of acts, each unlawful and dangerous but it cannot be shown which particular act was the actual cause of death.

    Court of Appeal held the defendant could be found guilty of manslaughter.

Mens rea

It must be proved the defendant had the mens rea for the unlawful act.

Newbury and Jones (1976)

Defendants, teenagers, had threw a paving stone from a railway bridge onto a train and killed the victim, a train guard. Defendants were convicted of manslaughter.

House of Lords upheld the conviction and confirmed it was not necessary to prove the defendant had known the act was unlawful or dangerous. It is sufficient to prove a defendant intentionally did an act which was unlawful and dangerous and that act caused death.

Le Brun (1991)

Defendant hit the victim, his wife, on the chin during an argument outside their house. He dragged her inside the house, in doing so he accidentally fractured her skull and she died. Defendant was convicted of manslaughter.

Court of Appeal upheld the conviction. Although the original act was not the direct cause of death both were part of the same sequence of events. The original punch was intentional that was sufficient mens rea.

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