Involuntary manslaughter is a legal term referring to the unintentional killing of a human being in a manner that is considered to be less culpable than murder. Generally, the law differentiates between levels of legal culpability, based on the person's state of mind at the time of the crime. Involuntary manslaughter refers to a death that has been committed without deliberation, premeditation or malice by the person being accused. Malice is the legal term referring to the state of mind when an act is committed, or the intent to do harm to another human being. There are two types of involuntary manslaughter: criminally negligent manslaughter and unlawful-act manslaughter, also known as constructive manslaughter.

In cases of criminally negligent manslaughter, someone is killed because of the negligence of another person. In this case, the degree of negligence required must be very high to warrant criminal liability. To constitute this type of involuntary manslaughter, the person must have performed an act that is legal, but showed a lack of reasonable skill or care in performing that act. As an example, a drunk driver that kills someone in an accident could be charged with criminally negligent manslaughter.

Failure to perform a duty, or an omission of an act, can also constitute criminal negligence leading to involuntary manslaughter. This applies to those people who have a job, or duty, that entails acting in a particular way under particular circumstances. If the person fails to act, that is when the person can be accused of criminal negligence. For example, medical doctors can be charged with criminal negligence in circumstances where a patient dies from the doctor failing to perform his or her duties.

In cases of unlawful-act manslaughter or constructive manslaughter, someone commits an act that is unlawful, but not a felony, which leads to a death. The intent was not to cause bodily harm or death, although the death would not have happened if the person had not committed the illegal act. For example, if a shopkeeper has a heart attack and dies because of the shock caused by an attempted robbery, then the robber may be charged with unlawful-act manslaughter. This type of involuntary manslaughter is sometimes called misdemeanor manslaughter.

The penalty for involuntary manslaughter is often imprisonment of some kind. The prison term depends on the applicable law in the jurisdiction that the crime is committed in, as well as the severity and type of crime committed. In most cases, the penalty for criminally negligent manslaughter is worse than the penalty for unlawful-act manslaughter.