Legal Dictionary

involuntary manslaughter

Definition of involuntary manslaughter

Further reading

Involuntary manslaughter is the unlawful killing of a human being without malice aforethought. It is distinguished from voluntary manslaughter by the absence of intention. It is normally divided into two categories; constructive manslaughter and criminally negligent manslaughter.

Constructive manslaughter

Constructive manslaughter is also referred to as ‘unlawful act' manslaughter. It is based on the doctrine of constructive malice, whereby the malicious intent inherent in the commission of a crime is considered to apply to the consequences of that crime. It occurs when someone kills, without intent, in the course of committing an unlawful act. The malice involved in the crime is transferred to the killing, resulting in a charge of manslaughter.

For example, a person who runs a red light in their vehicle and hits someone crossing the street could be found to intend or be reckless as to assault or criminal damage (see DPP v Newbury). There is no intent to kill, and a resulting death would not be considered murder, but would be considered involuntary manslaughter. The accused's responsibility for causing death is constructed from the fault in committing what might have been a minor criminal act.

United States law

In the United States, misdemeanor manslaughter is a lesser version of felony murder, and covers a person who causes the death of another while committing a misdemeanor - that is, a violation of law which doesn't rise to the level of a felony. This may automatically lead to a conviction for the homicide, if the misdemeanor involved a law designed to protect human life. Many violations of safety laws are infractions, which means a person can be convicted regardless of mens rea.

English law

Constructive manslaughter in English Law is committing an unlawful dangerous act which causes death. The associated doctrine of constructive murder, under which killing in the course of committing a felony led to a charge of murder, was abolished by the Homicide Act 1957.

There are three requirements for constructive manslaughter:

  • The defendant must do an unlawful act. This must be a criminal, not civil, offence and must involve mens rea of intention or recklessness. Crimes involving negligence or omission will not suffice.
  • The act must be dangerous. Whether the act is dangerous is objectively judged from the point of view of a sober and reasonable person present at the scene who witnessed the act. The defendant need not be aware the act is dangerous and the act need not be directed at the victim.
  • The act must cause the death of the victim.

Criminally negligent manslaughter

Criminally negligent manslaughter is variously referred to as criminally negligent homicide in the United States, gross negligence manslaughter in England and Wales. In Scotland and some Commonwealth of Nations jurisdictions the offence of culpable homicide might apply.

It occurs where death results from serious negligence, or, in some jurisdictions, serious recklessness. A high degree of negligence is required to warrant criminal liability. A related concept is that of willful blindness, which is where a defendant intentionally puts himself in a position where he will be unaware of facts which would render him liable.

Criminally negligent manslaughter occurs where there is an omission to act when there is a duty to do so, or a failure to perform a duty owed, which leads to a death. The existence of the duty is essential because the law does not impose criminal liability for a failure to act unless a specific duty is owed to the victim. It is most common in the case of professionals who are grossly negligent in the course of their employment. An example is where a doctor fails to notice a patient's oxygen supply has disconnected and the patient dies (R v Adomako).

United States law

In jurisdictions such as Pennsylvania, if a person is so reckless as to "manifest extreme indifference to human life", the defendant may be guilty of aggravated assault as well as of involuntary manslaughter.

In many jurisdictions such as California, malice may be found if gross negligence amounts to willful or depraved indifference to human life. In such a case, the wrongdoer may be guilty of second degree murder.

English law

In English law, gross negligence is the test for manslaughter. The crime was defined in R v Bateman as 'to show such disregard for life and the safety of others as to amount to a crime against the state and conduct deserving of punishment. In R v Adomako the House of Lords affirmed R v Bateman, and set out the five elements required for negligence:

  • A duty of care owed by the defendant to the victim.
  • A breach of that duty.
  • A risk that the defendant's conduct could cause death.
  • Evidence that the breach of duty caused the victim's death.
  • The defendant fell so far below the standards of the reasonable man in that situation that he should be labelled grossly negligent and deserving of criminal punishment.

It is for the jury to decide what constitutes 'grossly negligent behaviour'.


  1. Wiktionary. Published under the Creative Commons Attribution/Share-Alike License.


1.     quorum
2.     lex situs
3.     scienter
4.     AORO
5.     adjudication order
6.     lex causae
7.     Miranda warning
8.     lex domicilii
9.     appellant
10.     lex patriae