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 Kansas, manslaughter is categorized under the Kansas Statutes Annotated (K.S.A.) and is considered a serious felony offense. Kansas law recognizes both voluntary and involuntary manslaughter. Voluntary manslaughter, under K.S.A. 21-5404, is defined as the intentional killing of a human being committed: (a) upon a sudden quarrel or in the heat of passion, or (b) upon an unreasonable but honest belief that circumstances existed that justified deadly force. Involuntary manslaughter, under K.S.A. 21-5405, occurs when a person kills another human being unintentionally but recklessly under circumstances manifesting extreme indifference to the value of human life, or during the commission of a lawful act in an unlawful manner. Penalties for manslaughter in Kansas vary depending on the circumstances and degree of the offense, with involuntary manslaughter typically carrying less severe penalties than voluntary manslaughter. Sentencing can include lengthy prison terms, and the specific penalties are outlined in the state's sentencing guidelines.