Civilian casualties

Civilian casualties is a military term describing civilian persons killed, injured, or imprisoned by military action. Civilian casualties can be associated with the outcome of any form of military action regardless of whether civilians were targeted directly or not. This differs from collateral damage which specifically applies to only unintentional effects of military action including unintended casualties. Some researchers have included refugees and internally displaced persons in their definition of "civilian casualty".

Civilian casualties therefore include victims of atrocities such as the Nanking Massacre committed on a civilian population where hundreds of thousands of men were slaughtered, while girls and women ages ranging from 10 to 70 were systematically raped and/or killed by Japanese soldiers in 1937. Another example is the My Lai Massacre (thảm sát Mỹ Lai) that was committed by United States soldiers during the Vietnam War on hundreds of unarmed Vietnamese civilians. Such military action, which has the sole purpose of inflicting civilian casualties, is illegal under modern rules of war, and may be considered a war crime or crime against humanity.

Other kinds of civilian casualties may involve the targeting of civilian populations for military purposes, such as the atomic bombings of Hiroshima and Nagasaki, which killed over 150,000 people, although both cities contained major military installations and factories which were dispersed within civilian areas. The legality of such action was at the time governed by international law found in the 1907 Hague Regulations on Land Warfare, which states that "the attack or bombardment, by whatever means, of towns, villages, dwellings, or buildings which are undefended is prohibited." Also relevant, were the Hague Rules of Air Warfare of 1922–1923, which states that "an air bombardment is legitimate only when is directed against a military objective, i.e. an objective whereof the total or partial destruction would constitute an obvious military advantage for the belligerent", although the document was never adopted in a legally binding form. The Rome Statute defines that "intentionally directing attacks against the civilian population" to be illegal, but only came into effect on July 1, 2002 and has not been ratified by every country.

The ethics of civilian casualties
Many modern nations' views on the ethics of civilian casualties align with the Just War theory, which advocates a system of proportionality. An act of war is deemed proportional in Just War theory if the overall destruction expected from the use of force is outweighed by the projected good to be achieved. This view is a war-adapted version of utilitarianism, the moral system which advocates that the morally correct action is the one that does the most good.

However, moral philosophers often contest this approach to war. Such theorists advocate absolutism, which holds there are various ethical rules that are, as the name implies, absolute. One such rule is that non-combatants cannot be attacked because they are, by definition, not partaking in combat; to attack non-combatants anyway, regardless of the expected outcome, is to deny them agency. Thus, by the absolutist view, only combatants can be attacked. The philosopher Thomas Nagel advocates this abolutist rule in his essay War and Massacre.

Finally, the approach of pacifism is the belief that war of any kind is morally unjust. Pacifists sometimes extend humanitarian concern not just to enemy civilians but also to combatants, especially conscripts.

Civilian casualty ratio
The civilian casualty ratio in an armed conflict is the ratio of civilian casualties to combatant casualties or total casualties. The measurement can apply either to casualties inflicted by a particular belligerent or to casualties in the conflict as a whole.

The ratio of ten civilian casualties for every combatant is a frequently-cited, but disputed figure.