Legal Dictionary

voluntary manslaughter

Definition of voluntary manslaughter

Further reading

Voluntary manslaughter occurs either when the defendant kills with malice aforethought (intention to kill or cause serious harm), but there are mitigating circumstances which reduce culpability, or when the defendant kills only with an intent to cause serious bodily harm. Voluntary manslaughter in some jurisdictions is a lesser included offense of murder. The traditional mitigating factor was provocation; however, others have been added in various jurisdictions.

Voluntary manslaughter is the killing of a human being in which the offender had no prior intent to kill and acted during "the heat of passion", under circumstances that would cause a reasonable person to become emotionally or mentally disturbed. In the Uniform Crime Reports prepared by the Federal Bureau of Investigation, it is referred to as non negligent manslaughter. Voluntary manslaughter is one of two main types of manslaughter, the other being involuntary manslaughter.

Laws in the United States

There have been many types of voluntary manslaughter. These have not been differentiated here as they are so closely related or indistinguishable that many US jurisdictions do not differentiate between them. The following are some examples of defenses which may be raised to mitigate murder to voluntary manslaughter:

  • Provocation: A killing which occurs after provocation by an event which would cause a reasonable person to lose self-control. There must not be a cooling off period negating provocation. If there is an interval between the provocation and killing sufficient to allow the passion of a reasonable person to cool, the homicide is not manslaughter, but murder.
  • Imperfect self-defense: Allowed only in a limited number of jurisdictions in the United States, self-defense is a complete defense to murder. However, a person who acted in self defense with an honest but unreasonable belief that deadly force was necessary to do so could still be convicted of voluntary manslaughter or deliberate homicide committed without criminal malice. Malice is found if a person killed intentionally and without legal excuse or mitigation.
  • Diminished capacity is a defense which serves to negate the mental state of "malice". If a jurisdiction recognizes that a person can kill without justification, but also without any evil intent, for example due to a mental defect or mental illness, that jurisdiction is free to define the crime as something less than murder. This partial defense is only available in some US jurisdictions and not others; whereas the complete defense of insanity is available throughout the US, but rarely used because it is more difficult to show.

English law

The Homicide Act 1957 sets out three partial defences that reduce murder to voluntary manslaughter: diminished responsibility, provocation and suicide pact. Sections 52-56 of The Coroners and Justice Act 2009 will amend, and update, the partial defences of diminished responsibility and provocation (which will be renamed 'loss of control'), however, these provisions are not yet in force and no date has been set for them to become so.

Diminished responsibility

This covers diminished mental responsibility for a crime falling short of the requirements of the complete defence of Insanity. Under s 2 Homicide Act 1957 there are three requirements for the defendant to raise the defence of diminished responsibility:

  • The defendant suffered from an abnormality of mind at the time of the killing. An abnormality of mind is ‘a state of mind so different from that of ordinary human beings that the reasonable man would term it abnormal'.
  • The abnormality was caused by one of the causes specified by the Act: a condition of arrested or retarded development of mind, any inherent cause or a disease or injury.
  • The abnormality substantially impaired the defendant's mental responsibility for the killing. Substantial means the lack of control must simply be ‘more than trivial'.

Under s2(2) of the Act it is for the defendant to prove he suffered from such a condition on the balance of probabilities.


Provocation was originally a common law defense to murder, but it was reformed by s3 Homicide Act 1957. There are two limbs to the defence, first the defendant must have actually been provoked, and second the provocation must be such as would have made the reasonable man act as the defendant did. Provocation can come from someone other than the victim and be aimed at someone other than the accused. Further the defense is not defeated by the fact that the defendant induced the provocation.

  • Subjective limb: provocation in fact: It is a question of fact for the jury whether the defendant was in fact provoked. The loss of control must be sudden and temporary. However, it can be the result of slow burn with a relatively minor ‘final straw'.
  • Objective limb: the reasonable man test: The provocation must be enough to make a reasonable man do as the defendant did. The reasonable man has the same sex and age as the defendant and such characteristics as affect the gravity of the provocation to the defendant, but characteristics irrelevant to the provocation such as unrelated mental disorders are not given to the reasonable man. Finally, the reasonable man always has reasonable powers of self control and is never intoxicated.


  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