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 Colorado, homicide is categorized based on the circumstances and the intent behind the act. Murder, which involves intent and premeditation, is classified into first-degree murder and second-degree murder under Colorado law. First-degree murder (C.R.S. 18-3-102) is the most serious charge, requiring deliberation and intent, and can result in life imprisonment or the death penalty. Second-degree murder (C.R.S. 18-3-103) involves intent to cause death without premeditation and carries a lesser, but still severe, penalty. Manslaughter (C.R.S. 18-3-104), a less severe form of homicide, occurs when a person recklessly causes the death of another or intentionally causes or aids another person to commit suicide. Involuntary manslaughter, which is not specifically defined in Colorado statutes, would typically fall under the category of manslaughter in Colorado and involves unintentional killing due to reckless behavior. Vehicular homicide (C.R.S. 18-3-106) is charged when a death results from driving recklessly or under the influence of alcohol or drugs. The specific charges and penalties for homicide offenses in Colorado are detailed in the state's penal code and can vary based on the circumstances of each case.