Involuntary Manslaughter

Involuntary manslaughter is defined as an unintentional killing that results either from criminal negligence or the commission of a low-level criminal act such as a misdemeanor. Involuntary manslaughter is distinguished from other forms of homicide because it does not require deliberation or premeditation, or intent. Because neither of these mental states is required, involuntary manslaughter is the lowest level category of homicide.

Criminal Negligence

The first type of involuntary manslaughter occurs when a defendant negligently commits an act that results in the death of another. The level of negligence required for involuntary manslaughter is higher than normal civil negligence and requires that the defendant have acted in a very unreasonable manner.  The exact language used to describe this negligence standard varies by state, but many refer to it as “criminal negligence” or “gross negligence.” State laws also vary as to whether the defendant must have been aware that his conduct was grossly negligent. In some states, the defendant must have known that his conduct was a threat to others, while other states consider whether the actions were objectively negligent, without regard for the defendant’s own perceptions.

It is important to understand that criminal negligence does not require that the defendant have committed an unlawful act. Rather, it criminalizes both lawful and unlawful acts that are committed negligently. For instance, although driving a vehicle is legal, driving that vehicle in a reckless manner may constitute criminal negligence and, if death results, lead to a charge of involuntary manslaughter.

Criminal negligence can also result from a failure to perform an act that the defendant has a duty to perform. Where a parent has a duty to take care of and protect a child, but the child dies when she is left in the car on a hot day, the parent may be culpable for involuntary manslaughter. Another example would be a tour operator who fails to advise his passengers of the proper safety protocols, resulting in the death of a passenger. This tour operator has failed to perform his duty, resulting in criminal negligence.

Misdemeanor Manslaughter

The second form of involuntary manslaughter results from an unintentional killing that occurs during the commission of a misdemeanor or low-level felony that does not trigger the felony murder rule. The crimes that can trigger misdemeanor manslaughter will vary by state statute. Misdemeanors include those crimes that are less than a felony and that are typically punishable by a fine or less than one year in prison. In some states, a killing that occurs during any misdemeanor can lead to a misdemeanor manslaughter charge. In others, only a killing that occurs during more serious misdemeanors will result in manslaughter charges.

Additionally, it is important to check your state’s felony murder rule to determine what felonies are subject to the rule. A killing that occurs during a felony that is not encompassed within the felony murder rule may result in misdemeanor manslaughter charges instead.

Punishment and Defenses

As involuntary manslaughter may be charged in a wide range of circumstances, the punishment and defenses applied to involuntary manslaughter will vary widely by state. In federal court, an involuntary manslaughter charge can result in a sentence of imprisonment for one to six years, while many states provide for a range of sentences depending on the severity of the negligence or the underlying misdemeanor.

Because involuntary manslaughter does not require a showing of intent, a defendant cannot utilize the defense that he did not intend to commit the crime. A defendant can, however, argue that his actions did not rise to the level of negligence necessary to constitute criminal negligence. This may include arguing that the killing was truly an accident and did not result from the careless actions of the defendant. 

In the case of misdemeanor manslaughter, any defense to the underlying misdemeanor is also a defense to the misdemeanor manslaughter charge.  For example, if the defendant is charged with misdemeanor battery which results in death, but she successfully argues that the battery was self-defense, this would also be a defense to a misdemeanor manslaughter charge.