Homicide

thumb|[[Cain Slays Abel by Gustave Doré]]

Homicide is an act in which a person causes the death of another person. A homicide requires only a volitional act, or an omission, that causes the death of another, and thus a homicide may result from accidental, reckless, or negligent acts even if there is no intent to cause harm.

Homicides can be divided into many overlapping legal categories, such as murder, manslaughter, justifiable homicide, assassination, killing in war (either following the laws of war or as a war crime), euthanasia, and capital punishment, depending on the circumstances of the death. These different types of homicides are often treated very differently in human societies; some are considered crimes, while others are permitted or even ordered by the legal system.

Criminality

Criminal homicide takes many forms, including accidental killing and murder. Criminal homicide is divided into two broad categories—murder and manslaughter—based upon the state of mind and intent of the person who commits the homicide.

A report issued by the United Nations Office on Drugs and Crime in July 2019 documented that nearly 464,000 people around the world were killed in homicides in 2017, a number significantly in excess of the 89,000 killed in armed conflicts during the same period.

Murder

Murder is the most serious crime that can be charged following a homicide. In many jurisdictions, murder may be punished by life in prison or even capital punishment. Although categories of murder can vary by jurisdiction, murder charges fall under two broad categories, or degrees:

• First degree: The premeditated, unlawful, intentional killing of another person.
• Second degree: The intentional, unlawful killing of another person, but without any premeditation.

In some jurisdictions, a homicide that occurs during the commission of a dangerous crime may constitute murder, regardless of the actor's intent to commit homicide. In the United States, this is known as the felony murder rule. In simple terms, under the felony murder rule a person who commits a felony may be guilty of murder if someone dies as a result of the commission of the crime, including the victim of the felony, a bystander or a co-felon, regardless their intent—or lack thereof—to kill, and even when the death results from the actions of a co-defendant or third party who is reacting to the crime.

Preterintentional killing

The preterintentional killing occurs when a person, with actions aimed at hitting or harming, unintentionally causes the death of a person: the agent will be liable for objective responsibility (or fault, for the laws that require it) for the death event.

Manslaughter

Manslaughter is a form of homicide in which the person who commits the homicide either does not intend to kill the victim, or kills the victim as the result of circumstances that would cause a reasonable person to become emotionally or mentally disturbed to the point of potentially losing control of their actions. The distinction between murder and manslaughter is sometimes said to have first been made by the ancient Athenian lawmaker Draco in the 7th century BC. The penalty for manslaughter is normally less than the penalty for murder. The two broad categories of manslaughter are:

Lawful excuse

Not all homicides are crimes, or subject to criminal prosecution. Some are legally privileged, meaning that they are not criminal acts at all. Others may occur under circumstances that provide the defendant with a full or partial defense to criminal prosecution. Common defenses include:

• Self-defense: while most homicides by civilians are criminally prosecutable, a right of self-defense (often including the right to defend others) is widely recognized, including, in dire circumstances, the use of deadly force.
• Mental incapacity: A defendant may attempt to prove that they are not criminally responsible for a homicide due to a mental disorder. In some jurisdictions, mentally incompetent killers may be involuntarily committed in lieu of criminal trial. Mental health and development are often taken into account during sentencing. For example, in the United States, the death penalty cannot be applied to convicted murderers with intellectual disabilities.
• Defense of infancy – Small children are not held criminally liable before the age of criminal responsibility. A juvenile court may handle defendants above this age but below the legal age of majority, though because homicide is a serious crime some older minors are charged in an adult justice system. Age is sometimes also taken into account during sentencing even if the perpetrator is old enough to have criminal responsibility.
• Justifiable homicide or privilege: Due to the circumstances, although a homicide occurs, the act of killing is not unlawful. For example, a killing on the battlefield during war is normally lawful, or a police officer may shoot a dangerous suspect in order to protect the officer's own life or the lives and safety of others.

The availability of defenses to a criminal charge following a homicide may affect the homicide rate. For example, it has been suggested that the availability of "stand your ground" defense has resulted in an increase in the homicide rate in U.S. jurisdictions that recognize the defense, including Florida.

By state actors

Homicides committed by state actors may be considered lawful or unlawful according to:

• Municipal law
• International law to which the state has agreed to via treaty
• Peremptory norms which are de facto enforced as obligatory on all states, such as prohibitions against genocide, piracy and slavery

Types of state killings include:

• Capital punishment, where a judicial system of a state authorizes the death penalty as punishments for certain crime, though many countries have abolished it completely
• Lawful killings during war, such as the killing of enemy combatants
• Lawful use of deadly force by security forces (such as law enforcement officers or military personnel) to maintain public safety in emergency situations
• Extrajudicial killings, where state actors kill people (typically individuals or small groups) without judicial court proceedings
• War crimes that involve killing (war crimes not authorized by the state may also be committed by individuals who are then subject to domestic military justice)
• Widespread, systematic killing of a particular group of people by the state, which depending on the target, could be called genocide, politicide or classicide. In some cases these events may also meet the definition of a crime against humanity.

The term mass killing has been proposed by genocide scholars as a concept to define certain large-scale killings of non-combatants by state actors. Some medium- and large-scale mass killings by state actors have been termed massacres, though not all such killings have been so named. The term "democide" was coined by American political scientist Rudolph Rummel to describe "murder by government" in general, which included both extrajudicial killings and widespread systematic acts of homicide. Killings committed by state actors might be called "murder" or "mass murder" in general usage, especially if seen by the commentator as unethical, but the domestic legal definitions of murder, manslaughter, etc., usually exclude killings carried out by lawful government action.

Dartmouth College professor Benjamin Valentino outlines two major categories of mass killings: dispossessive mass killing and coercive mass killing. The first category includes four subcategories: communist, fascist, ethnic and territorial mass killings, while second category includes counterinsurgency, terrorist and imperialist mass killings. Valentino included several prominent examples of dispossessive mass killing to include his arguments, including the Holodomor, Great Leap Forward and Cambodian genocide for communist mass killings, the White Terror, the Holocaust and Dirty War for fascist mass killings, the Armenian and Rwandan genocides for ethnic mass killings and the American Indian Wars and Herero and Nama genocide for territorial mass killings. He also included examples of coercive mass killings, including counterinsurgency killings during the Algerian War and Soviet–Afghan War, terrorist mass killings such as strategic bombing during World War II and the blockade of Biafra, and German and Japanese imperialism during World War II as examples of imperialist mass killings.

Rates

Global

thumb|upright=1.2|A map of countries by their intentional homicide rate per 100,000 people. Latest available year up to year on map. From [[Our World in Data. Data: United Nations Office on Drugs and Crime.]]