Distinction (law)

Distinction is a principle under international humanitarian law governing the legal use of force in an armed conflict, whereby belligerents must distinguish between combatants and civilians. Distinction and proportionality are important factors in assessing military necessity in that the harm caused to civilians or civilian property must be proportional and not "excessive in relation to the concrete and direct military advantage anticipated" by an attack on a military objective.

Codification
Distinction is covered by Protocol I (Additional to the Geneva Conventions), Chapter II: "Civilians and Civilian Population". Article 50 defines who is a civilian and what is a civilian population; article 51 describes the protection which should be given to civilian populations; and chapter III regulates the targeting of civilian objects. Article 8(2)(b)(i) of the Rome Statute of the International Criminal Court also prohibits attack directed against civilians. Not all states have ratified Protocol I or the Rome Statute, but it is an accepted principle of international humanitarian law that the direct targeting of civilians is a breach of the customary laws of war and is binding on all belligerents.

Luis Moreno-Ocampo was the Chief Prosecutor at the International Criminal Court who investigated allegations of war crimes during the 2003 invasion of Iraq. He published an open letter containing his findings; in a section titled "Allegations concerning War Crimes", he elucidates this use of distinction: