The distinction between murder and manslaughter is sometimes said to have first been made by the ancient Athenian lawmaker Draco in the 7th century BC.
For voluntary manslaughter, the offender had intent to kill or seriously harm, but acted "in the moment" under circumstances that could cause a reasonable person to become emotionally or mentally disturbed.
[2] There are mitigating circumstances that reduce culpability, such as when the defendant kills only with an intent to cause serious bodily harm.
For example, a person who fails to stop at a red traffic light while driving a 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[10]).
The accused's responsibility for causing death is constructed from the fault in committing what might have been a minor criminal act.
The DPP v Newbury case had redefined the meaning of murder in the Australian constitution, and reformed in order to include a mens rea assessment.
A person who is driving carefully, but whose car nevertheless hits a child darting out into the street, has not committed manslaughter.
A person who pushes off an aggressive drunk, who then falls and dies, has probably not committed manslaughter, although in some jurisdictions it may depend on whether "excessive force" was used or other factors.
In Australia, specifically New South Wales, manslaughter is referred to, however not defined, in the Crimes Act 1900 (NSW).
In New South Wales, in cases of voluntary manslaughter, both the actus reus (literally guilty act) and mens rea (literally guilty mind) for murder are proven but the defendant has a partial defence, such as extreme provocation or diminished responsibility.
[30][11]: [51]–[65] In cases of involuntary manslaughter, the actus reus for murder is present but there is insufficient mens rea to establish such a charge.
Manslaughter by criminal negligence, on the other hand, finds its authority in the Victorian case of Nydam v R,[32] confirmed by the High Court of Australia in R v Lavender[14] and Burns v R.[33] In Nydam v R,[32] the Court described the office at [445] in the following terms:In order to establish manslaughter by criminal negligence, it is sufficient if the prosecution shows that the act which caused the death was done by the accused consciously and voluntarily, without any intention of causing death or grievous bodily harm but in circumstances which involved such a great falling short of the standard of care which a reasonable man would have exercised and which involved such a high risk that death or grievous bodily harm would follow that the doing of the act merited criminal punishment.
[35] Criminal negligence is when the homicide was the result of an act that showed wanton or reckless disregard for the lives of others.
In England and Wales, the usual practice is to prefer a charge of murder, with the judge or defence able to introduce manslaughter as an option (see lesser included offence).
Voluntary manslaughter occurs when the defendant avails themself of two statutory defences described in the Homicide Act 1957 (diminished responsibility and a suicide pact; provocation was a third but this was replaced by loss of control in 2010).
Involuntary manslaughter occurs when the agent has no intention (mens rea) of committing murder but caused the death of another through recklessness or criminal negligence.
):[53][54] A legal distinction between intentional and unintentional homicide was introduced in Athenian law in 409 BC,[55] when the legal code of Draco indicated that intentional homicide (hekousios phonos or phonos ek pronoias) was punishable by death.
[58] Murdra was a separate type of aggravated (secret) homicide under Anglo-Saxon law; William the Conqueror defined it narrowly as a fine that would be charged on a hundred following the slaying of a foreigner (originally a Norman, but intermarriage would end the distinction between Normans and English by the 13th century).