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 Nebraska, manslaughter is defined under Nebraska Revised Statute 28-305. The state recognizes manslaughter as the unlawful killing of a human being without malice upon a sudden quarrel or causing the death unintentionally while in the commission of an unlawful act. Nebraska does not explicitly categorize manslaughter into voluntary and involuntary types as some other states do. However, the circumstances described in the statute can encompass both concepts, where a killing in the heat of passion or during a sudden quarrel could be seen as voluntary manslaughter, and an unintentional death during an unlawful act might be considered involuntary manslaughter. Manslaughter in Nebraska is considered a Class IIA felony, which can result in a prison term of up to 20 years. The specific circumstances of the offense and the presence of any aggravating factors can influence the severity of the punishment upon conviction.