At common law, voluntary manslaughter is defined as the intentional killing committed in "sudden heat of passion" as the result of "adequate provocation."
- i.e. Killing another without malice aforethought.
There are four elements to common law manslaughter:
Heat of Passion
Acting in heat of passion means acting under the effect of a intense emotion such as fear, jealousy, or desperation instead of acting under reason.
To satisfy the element of manslaughter, the defendant must have acted in heat of passion at the moment of the homicide.
It is up to the jury to determine what constitutes adequate provocation, but they are typically instructed to apply an objective "reasonable person" standard.
In most jurisdictions, words are never adequate provocation.
- The defendant must not have had a reasonable opportunity to cool off.
- There must be a causal link between the provocation, passion, and homicide.
Model Penal Code
MPC § 210.3(1)
- Criminal homicide constitutes manslaughter when:
- it is committed recklessly; or
- a homicide which would otherwise be murder is committed under the influence of extreme mental or emotional disturbance for which there is reasonable explanation or excuse. The reasonableness of such explanation or excuse shall be determined from the viewpoint of a person in the actor's situation under the circumstances as he believes them to be.
Extreme Mental or Emotional Disturbance
MPC § 210.3(1)(b)
[Criminal homicide constitutes manslaughter when] a homicide which would otherwise be murder is committed under the influence of extreme mental or emotional disturbance for which there is reasonable explanation or excuse. The reasonableness of such explanation or excuse shall be determined from the viewpoint of a person in the actor's situation under the circumstances as he believes them to be.
The concept of EMED is intended to incorporate the two common law doctrines of sudden heat of passion (but greatly expanded) and partial responsibility due to diminished capacity.
EMED is broader than the common law provocation defense because:
- A specific provocative act is not required.
- Even if there is a provocation, it need not involve "an injury, affront, or other provocative act perpetrated upon [the defendant] by the decedent."
- Even if the decedent provoked the incident, it need not fall within any fixed category of provocations.
- Words alone can warrant a manslaughter instruction.
- There is no rigid cooling-off rule. The suddenness requirement of the common law—that the homicide must follow almost immediately after the provocation—is absent form the EMED defense.
Involuntary manslaughter is a common law offense of killing either through recklessness, but without an extreme indifference to human life, or through gross negligence.
It requires either recklessness by consciously disregarding a substantial and unjustifiable risk to human life or gross negligence in failing to be aware of a substantial and unjustifiable risk to human life and committing an act exhibiting a callous disregard for human life.
Grossly Negligent Involuntary Manslaughter
One commits involuntary manslaughter when he kills another through a gross deviation from the standard of care that reasonable people would exercise in the situation.
It is more than tortuous negligence; it must be "so gross" as to be deserving of criminal punishment.
The Model Penal Code does not recognize gross negligence as a basis for involuntary manslaughter, but has a separate offense of negligent homicide.
When one kills another through an act that exhibits extreme indifference to human life, the difference between reckless murder and involuntary manslaughter is that reckless murder requires that the defendant consciously disregard the risk, while involuntary manslaughter only requires that he be grossly negligent by be being unaware of a substantial and unjustifiable risk to human life.
Reckless Involuntary Manslaughter
If one is aware of a substantial and unjustifiable risk to human life and disregards it anyway (recklessness), but his act does not exhibit extreme indifference to human life, he is guilty of involuntary manslaughter.
This is also manslaughter under the Model Penal Code.