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 Oregon, homicide is defined as causing the death of another person and can be classified into different categories based on the circumstances and the intent of the perpetrator. Murder, which is intentional homicide, is further divided into degrees. First-degree murder involves premeditation and intent, while second-degree murder involves intent but without premeditation. Manslaughter in Oregon is categorized as either first or second degree. First-degree manslaughter occurs when a person intentionally causes the death of another under circumstances that do not constitute murder, such as extreme emotional disturbance, while second-degree manslaughter is typically due to recklessness or criminal negligence, such as causing a death by recklessly operating a vehicle. Oregon also recognizes the affirmative defenses of self-defense and insanity, which can justify a homicide and result in a lawful killing. The specific charges and penalties for homicide offenses are detailed in Oregon's criminal statutes, and the severity of the charge will depend on factors such as intent, premeditation, and the presence of any mitigating circumstances.