Homicide is the act of one person causing the death of another person. Not all homicides are murder—some are manslaughter due to mitigating circumstances—and some are lawful when justified by an affirmative defense such as self-defense or insanity.

Criminal homicide generally involves (1) intent to cause death or serious bodily injury, or (2) negligence that causes the death of another person. Criminal homicide committed with the intent to cause death or serious bodily injury is generally charged as the criminal offense of murder (committed with intent and with premeditation or malice) or as voluntary manslaughter or second degree murder (committed with intent but without premeditation or malice).

And criminal homicide caused by negligence is generally charged as the criminal offense of involuntary manslaughter—for example, when a person is driving recklessly or speeding and hits another motor vehicle or pedestrian, causing the death of the other motorist or the pedestrian. A person driving a motor vehicle while intoxicated by drugs or alcohol who hits another motor vehicle or pedestrian, causing the death of the other motorist or the pedestrian, may be charged with involuntary manslaughter, or with a more specific offense like intoxication manslaughter or vehicular homicide—depending on applicable state laws.

Criminal homicide laws vary from state to state—including the names, degrees of severity, and punishments. These laws are generally found in a state’s statutes—often in the penal or criminal code.

In Illinois, homicide is considered the unlawful killing of another person and is categorized into different offenses based on the circumstances and the intent of the perpetrator. Murder, which is the most serious form of homicide, requires intent to kill or do great bodily harm, or knowledge that the act will cause death or great bodily harm. Illinois distinguishes between first-degree murder, which involves premeditation or a specific intent to kill, and second-degree murder, which is similar to voluntary manslaughter in other jurisdictions, where the offender acts under a sudden and intense passion resulting from serious provocation. Involuntary manslaughter, on the other hand, occurs when an individual unintentionally kills another person due to reckless behavior, such as in the case of a fatal car accident caused by reckless driving or driving under the influence of drugs or alcohol. Illinois law also recognizes the affirmative defenses of self-defense and insanity, which can justify a homicide or lead to an acquittal. The specific statutes detailing homicide laws in Illinois can be found in the Illinois Compiled Statutes under the Criminal Code of 2012.