Voluntary Manslaughter (Heat of Passion)

Voluntary manslaughter is an intentional killing that occurs under circumstances that partially excuse the defendant's conduct, reducing what would otherwise be murder to a lesser offense. The most common form is a killing committed in the heat of passion upon adequate provocation. The doctrine recognizes that while the killing is intentional and unlawful, the defendant's emotional state at the time, triggered by provocation, makes them less culpable than a premeditated murderer.

At common law, four requirements must be met. First, there must be adequate provocation, which is provocation sufficient to cause a reasonable person to lose self-control. Traditional categories of adequate provocation include being subjected to a serious battery, discovering a spouse in the act of adultery, witnessing an assault on a close relative, and being subjected to an unlawful arrest. Mere words alone were traditionally insufficient, though the modern trend has moved toward a more flexible standard. Second, the defendant must have actually been provoked and acted in the heat of passion. Third, there must be no sufficient cooling-off period between the provocation and the killing; the killing must occur before a reasonable person would have regained self-control. Fourth, the defendant must not have actually cooled off.

The Model Penal Code replaces heat of passion with the broader concept of extreme mental or emotional disturbance (EMED), for which there is a reasonable explanation or excuse. The reasonableness is judged from the viewpoint of a person in the defendant's situation under the circumstances as the defendant believed them to be. The MPC approach is more flexible: it does not require a specific provoking event, there is no rigid cooling-off period, and words alone can suffice. The burden is on the defendant to prove EMED by a preponderance of the evidence.