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 Iowa, manslaughter is categorized under the broader term of 'homicide' and is addressed in the Iowa Code. Iowa law recognizes involuntary manslaughter as a distinct offense, which is the unintentional killing of another person resulting from 'reckless' behavior. It is classified as a Class D felony, which can result in a prison sentence of up to five years and a fine. Voluntary manslaughter, on the other hand, is not specifically defined in Iowa statutes; however, cases that might be considered voluntary manslaughter in other jurisdictions could be prosecuted under different charges such as murder or assault causing serious injury, depending on the circumstances and the presence of any mitigating factors, such as acting in the heat of passion. The specific classification and penalties for homicide offenses in Iowa depend on the facts of the case and the degree of intent or recklessness involved. It is important to consult an attorney for detailed legal advice and representation in cases involving manslaughter charges in Iowa.