Substantive Criminal Law § 15.2. Heat-of-passion voluntary manslaughter
Voluntary manslaughter in most jurisdictions consists of an intentional homicide committed under extenuating circumstances which mitigate, though they do not justify or excuse, the killing. The principal extenuating circumstance is the fact that the defendant, when he killed the victim, was in a state of passion engendered in him by an adequate provocation (i.e., a provocation which would cause a reasonable man to lose his normal self-control).
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(1) Battery. A light blow, though it may constitute a battery, can not constitute a reasonable provocation;24 but a violent, painful blow, with fist or weapon, ordinarily will do so.25 Even in the case where the defendant kills in response to a violent blow, however, he may not have his homicide reduced to voluntary manslaughter if he himself by his own prior conduct (as by vigorously starting the fracas) was responsible for that violent blow.26 Something too may depend upon a comparison of the weapon used by the victim to inflict the blow upon the killer and the weapon which the latter “used in retort,”27 as where a dagger is used in retaliation for a blow with a fist,28 or five lethal slashes with a straight razor for one wifely blow on the head with a small fireplace poker.29