Homicide is the killing of one human being by another. The word describes the act, not the legal outcome. A homicide can be a crime, but it can also be lawful, as when a person uses deadly force in self-defense or a police officer uses force in the line of duty. Criminal law sorts homicides into categories based on the killer's state of mind, the circumstances, and the degree of fault. Those categories carry very different penalties, so the classification often decides the outcome of a case.
The Core Categories
Most jurisdictions divide homicide into murder, manslaughter, and killings that are justifiable or excusable. The details vary by state, but the structure is broadly similar.
| Category | Key feature | Typical examples |
|---|---|---|
| First degree murder | Premeditation, or killing during certain felonies | Deliberate killing, felony murder, killing by poison or lying in wait |
| Second degree murder | Malice without premeditation | Intent to kill in the heat of the moment, extreme recklessness |
| Voluntary manslaughter | Killing without malice, often from provocation | Killing in a sudden heat of passion |
| Involuntary manslaughter | Killing from criminal negligence | Reckless driving causing death |
| Justifiable or excusable | No criminal liability | Self-defense, accident without negligence |
Murder and Malice
Murder is an unlawful killing committed with malice aforethought. Malice does not require hatred or an intent to kill in every case. Courts recognize several forms: an intent to kill, an intent to cause serious bodily injury, a reckless disregard for human life that shows a depraved heart, and an intent to commit a felony during which a death occurs. That last form leads to the felony murder rule.
Many states divide murder into degrees. First degree murder usually requires premeditation and deliberation, or a killing committed during one of a list of serious felonies. Second degree murder covers all other murders, including killings committed with an intent to injure or with extreme recklessness. A few states use a third degree, and the labels and definitions differ from state to state.
Manslaughter
Manslaughter is an unlawful killing without malice. Voluntary manslaughter typically involves an intentional killing committed in a sudden heat of passion after adequate provocation, or in some states an imperfect self-defense claim. The idea is that the defendant's judgment was overwhelmed by circumstances that would stir a reasonable person, which reduces the moral blame. Involuntary manslaughter covers killings caused by criminal negligence or by a lawful act done in an unlawful manner. Vehicular homicide is a related offense in many states, sometimes charged as a separate crime with its own elements.
The Felony Murder Rule
Under the felony murder rule, a death that occurs during the commission of certain felonies can be charged as murder, even if the killing was accidental and the defendant did not intend it. The rule varies widely. Some states limit it to a short list of inherently dangerous felonies, such as robbery, burglary, arson, rape, and kidnapping. Others restrict it when the death is caused by a co-participant or a police officer. A few states have abolished it. The rule is controversial because it can impose serious liability for an unintended death, and courts and legislatures have narrowed it over time.
Justifiable and Excusable Homicide
Not every killing is a crime. Justifiable homicide includes killing in self-defense or defense of others when the use of deadly force is reasonable and necessary, and killings by law enforcement officers acting within the law. Excusable homicide includes accidents and misfortunes that occur without criminal negligence. The difference matters for how the case is charged and for the record. The exact rules on self-defense, including stand-your-ground and duty-to-retreat provisions, vary by state.
Causation
A homicide charge requires proof that the defendant's conduct caused the death. Prosecutors must show both actual cause, meaning the death would not have happened without the conduct, and proximate cause, meaning the death was a foreseeable result and not too remote. Intervening events, such as a victim's refusal of medical care, can complicate the analysis. Many states once followed a year-and-a-day rule, which barred a homicide charge if the victim died more than a year and a day after the act. Most jurisdictions have repealed or modified that rule as medicine has advanced.
Homicide in Federal Law
Federal homicide offenses are codified in Title 18 of the United States Code. Section 1111 defines murder and divides it into first and second degree, with first degree including premeditated killings and killings committed during certain enumerated felonies. Section 1112 defines manslaughter, and Section 1113 covers attempted murder and conspiracy to murder. Federal jurisdiction generally requires a special basis, such as the killing occurring on federal property, involving a federal official, or during another federal offense. The text of these statutes is available at govinfo.gov and congress.gov.
Penalties and the Role of the Charge
The penalty for a homicide conviction depends on the category and the jurisdiction. Sentences range from probation or a short term for some negligent killings to life imprisonment, and in a small number of jurisdictions and cases, the death penalty. Because the category drives the sentence, the fight in many homicide cases is about the charge and the mental state, not about whether a death occurred. Prosecutors and defense lawyers focus on intent, provocation, and the specific elements the government must prove.
Where to Learn More
State criminal codes are published on state legislature websites, and the state court system's self-help pages explain local procedure. Cornell's Legal Information Institute at law.cornell.edu offers free overviews of murder, manslaughter, and criminal law defenses. Federal statutes are at govinfo.gov and congress.gov. Because definitions and degrees differ, the statute in the charging jurisdiction is the place to confirm how a killing is classified.
This guide is general information about the law and is not legal advice. Homicide law varies by jurisdiction and turns on the facts, and anyone facing a charge should consult a licensed attorney.