Involuntary Manslaughter

Involuntary manslaughter is the unintentional killing of another person through criminal negligence or during the commission of an unlawful act that does not rise to the level of a dangerous felony (which would trigger felony murder). It occupies the lowest rung of criminal homicide, below both murder and voluntary manslaughter, reflecting the absence of intent to kill or subjective awareness of a high probability of death.

Criminal negligence, the more common basis for involuntary manslaughter, requires a gross deviation from the standard of care that a reasonable person would exercise. It is more culpable than civil negligence, requiring a higher degree of risk and a more significant departure from reasonable behavior. Courts often describe it as conduct showing a wanton or reckless disregard for human life, though importantly, the defendant need not have been subjectively aware of the risk (distinguishing it from reckless conduct). Examples include deaths caused by grossly negligent driving, failure to provide medical care, or unsafe handling of firearms.

The misdemeanor-manslaughter rule (sometimes called the unlawful act doctrine) imposes involuntary manslaughter liability when a death occurs during the commission of a misdemeanor or a non-dangerous felony that does not qualify for the felony murder rule. This parallels the felony murder rule but at a lower level. Some jurisdictions limit this to malum in se offenses (inherently wrongful acts) rather than malum prohibitum offenses (acts wrong only because prohibited by statute). The Model Penal Code categorizes unintentional killings based on the mental state: reckless homicide is manslaughter, while negligent homicide is a separate, lesser offense.