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Involuntary Manslaughter Lecture Notes


Involuntary manslaughter is the term given to an unlawful killing where the necessary mens rea for murder is not present - the defendant will not have had any intention to kill or do g.b.h. In fact, the defendant will probably not have contemplated the death of the victim at all. There are three broad categories of involuntary manslaughter:

  • Manslaughter by an unlawful and dangerous act (also known as constructive manslaughter),
  • Manslaughter by gross negligence, and
  • Manslaughter with subjective recklessness as to the risk of death or bodily harm.

As with voluntary manslaughter, if a defendant is convicted of involuntary manslaughter the sentence is at the discretion of the trial judge and can range between life imprisonment and an unconditional discharge.





This type of manslaughter is committed when the defendant has caused the death of a person by an unlawful and dangerous act. The Court of Appeal in R v Mitchell [1983] 2 WLR 938 (below) said that to establish this type of manslaughter it had to be shown:

1. that the accused had committed an unlawful act;
2. that the act was dangerous in the sense that a sober and reasonable person would inevitably recognise that it carried some risk of harm;
3. that the act was a substantial cause of death; and 
4. that the accused intended to commit the act as distinct from intending its consequence.



Since the decision in R v Franklin (1883) 15 Cox CC 163, unlawful act manslaughter must be based on a criminal act. Therefore, if the prosecution cannot establish a criminal act on the part of the defendant, the defendant will not be liable for unlawful act manslaughter. Compare:

R v Lamb [1967] 2 QB 981
R v Arobieke [1988] Crim LR 314.

The consent of the victim will not prevent an act from being unlawful. See:

R v Cato [1976] 1 WLR 110.



The act must be dangerous in the sense that the average person would recognise that it could cause some form of physical harm to another person. See:

R v Church [1966] 1 QB 59.

What type of harm has to be reasonably foreseeable?

The jury must be directed to consider the possibility of physical harm as opposed to merely emotional harm. See:

R v Dawson (1985) 81 Cr App R 150.

How much knowledge of the circumstances does one attribute to the bystander?

* In R v Watson [1989] 1 WLR 684, it was held that the sober and reasonable" bystander was to be endowed with whatever knowledge the defendant possessed.

* In R v Ball [1989] Crim LR 730, however, it was emphasised that the sober and reasonable bystander could not be endowed with any mistaken belief held by the defendant.



The unlawful and dangerous act must be a substantial cause of death.

Must the act be directed at the victim?

It had been suggested that because the unlawful act must expose the victim to the risk of some bodily harm, it must be aimed at that victim. See:

R v Dalby [1982] 1 WLR 425.

This seemed to introduce an extra element of mens rea into the offence by requiring the defendant to 'direct' his action against the victim. The significance of Dalby has been greatly reduced however, by the two following cases. The issue is now one of causation. See:

R v Mitchell [1983] 2 WLR 938
R v Goodfellow (1986) 83 Cr App R 23
R v Watson [1989] 1 WLR 684.



The mens rea for unlawful act manslaughter consists of mens rea as to the unlawful act itself (ie, intention or recklessness depending on what the necessary mens rea is for the act). The defendant need not realise the risk of causing some harm. As long as the reasonable man in his position would have so realised, this is sufficient mens rea. The House of Lords reaffirmed this point in:

DPP v Newbury and Jones [1976] AC 500.

If there is no mens rea for the unlawful act the defendant will not be liable; see R v Lamb (above).


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