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 Pennsylvania, manslaughter is categorized into two types: voluntary and involuntary manslaughter, as defined under Title 18 of the Pennsylvania Consolidated Statutes. Voluntary manslaughter (Section 2503) occurs when a person kills another without lawful justification if, at the time of the killing, the actor is acting under a sudden and intense passion resulting from serious provocation by the individual killed. Involuntary manslaughter (Section 2504) occurs when a person causes the death of another by acting in a reckless or grossly negligent manner. This can include situations such as causing a fatal accident due to driving under the influence of alcohol or drugs. Manslaughter is considered a felony in Pennsylvania, and the penalties can be severe, including lengthy prison terms. The specific classification of the felony and the associated penalties can vary based on the circumstances of the case and the presence of any aggravating factors.