Manslaughter is the unlawful killing or homicide of a human being without the premeditation or malice (malice aforethought) required for the criminal offense of murder. Many states have two types of manslaughter: (1) voluntary manslaughter—the defendant intended to kill the victim, but did so in self-defense, or in the heat of passion and without premeditation, or the defendant was insane and did not understand that the killing was wrong; and (2) involuntary manslaughter—the defendant negligently or recklessly caused the death of another person—such as when a person is intoxicated while operating a motor vehicle and causes an accident that results in the death of another person.

Some states do not have separate criminal offenses for voluntary and involuntary manslaughter—these states may have the offense of manslaughter and identify certain aggravating factors that may enhance the penalties upon a conviction for manslaughter. Manslaughter is a felony offense and may be punished by a lengthy prison term. Manslaughter laws are generally located in a state's statutes—often in the penal or criminal code.

In New Jersey, manslaughter is categorized under N.J.S.A. 2C:11-4 as either aggravated manslaughter or manslaughter. Aggravated manslaughter, the more serious form, occurs when someone causes a death under circumstances manifesting extreme indifference to human life. Manslaughter in New Jersey can also be voluntary, occurring in the heat of passion resulting from a reasonable provocation, or involuntary, where the death is caused by the defendant's reckless behavior. New Jersey does not use the terms 'voluntary' or 'involuntary' manslaughter, but the concepts are embedded within the manslaughter statute. Manslaughter is considered a second-degree offense, while aggravated manslaughter can be a first-degree offense, depending on the circumstances. Penalties for manslaughter in New Jersey can be severe, including lengthy prison terms, with aggravated manslaughter carrying up to a 30-year prison sentence and manslaughter carrying a 5 to 10-year prison sentence. These offenses are felonies and are prosecuted under the state's criminal justice system.