"The division of world society into national and international is an arbitrary one," in the words of the political scientist John Burton, but a division nonetheless clung to by much of international humanitarian law.

Because the traditional laws of war—and laws of war crimes—concerned only conflicts between States, States accusing each other of violating them or of committing war crimes needed to characterize a conflict as truly international and not internal. Thus, the Geneva Conventions and Additional Protocol I address in nearly all their aspects international conflicts only. They apply in the event of "declared war or of any other armed conflict [between States] even if the state of war is not recognized by one of them," as well as "all cases of partial or total occupation of the territory of a [State], even if the said occupation meets with no armed resistance." The easy cases involve invasion, assault, artillery bombardment, or air raid by one State against another; but the harder cases turn upon the perspectives of the belligerents and States observing the situation.

One such hard case, all too typical these days, is a civil war with foreign involvement or provocation, but without the foreign State's resort to the classic acts of war. What level of such involvement in a case like Bosnia or Zaire is enough to trigger the Geneva Conventions? International law offers no precise answers to this question. The International Court of Justice has held that a foreign State is responsible for the conduct of a faction in a civil war if (a) the faction is a de facto agent of the foreign State or (b) the foreign State otherwise orders it to commit certain acts. The UN's Yugoslavia Tribunal held in the Tadic case in 1997 that the de facto agent standard applied to trigger the Geneva Conventions; it went on to find that the Bosnian Serb army in that particular case was not a de facto agent of Serbia, that Serbia was thus not a party to the conflict, and that the conventions did not apply. The International Committee of the Red Cross Commentary to the Geneva Conventions suggests a lower standard, focusing on who had made the decision leading to the illegal acts. The issue remains unresolved.

The legal consequences of characterizing a conflict as solely internal have been quite significant. First, the Geneva Conventions provide only very basic protections in the event of civil wars through Article 3 common to the conventions. That article prohibits certain flagrant violations of human dignity like murder, torture, ill-treatment, and taking of hostages. Second, Additional Protocol II of 1977, which specifically addresses internal conflicts, provides fewer protections during such conflicts than the Geneva Conventions do for international conflicts. Third, for prosecution of war crimes, the conventions create criminal liability only for violations committed in international armed conflicts.

Nevertheless, recent developments have shown the possibility of prosecuting war crimes in internal conflicts without having to find some sort of linkage to an international war, through reliance on special statutes and customary international law. First, the Rwanda Tribunal statute explicitly gives that court jurisdiction over serious violations of Common Article 3 and Additional Protocol II; second, the Yugoslavia Tribunal has interpreted its Statute to allow for jurisdiction over serious violations of Common Article 3 and other serious violations of the laws and customs of war in internal conflicts; and third, the statute of the International Criminal Court specifically provides for criminality over many acts committed in internal conflicts.

(see gray areas in international humanitarian law; guerrillas; paramilitaries.)

Article 3 Common to the Four Geneva Conventions of 1949

Article 3, the text of which is repeated in all four Geneva Conventions, is the only part of the conventions that applies explicitly to internal armed conflicts. It has been called a "treaty in miniature," and sets forth the minimum protections and standards of conduct to which the State and its armed opponents must adhere. The protections it spells out are at the core of international humanitarian law. Additional Protocol II of 1977 also covers internal armed conflicts, but it is less widely accepted among States than the 1949 Conventions.

In the case of armed conflict not of an international character occurring in the territory of one of the High Contracting Parties, each Party to the conflict shall be bound to apply, as a minimum, the following provisions:

1. Persons taking no active part in the hostilities, including members of the armed forces who have laid down their arms and those placed hors de combat by sickness, wounds, detention, or any other cause, shall in all cases be treated humanely, without any adverse distinction founded on race, color, religion or faith, sex, birth of wealth, or any other similar criteria.

To this end the following acts are and shall remain prohibited at any time and in any place whatsoever with respect to the above-mentioned persons:

(a) violence to life and person, in particular murder of all kinds, mutilation, cruel treatment and torture;

(b) taking of hostages;

(c) outrages upon personal dignity, in particular humiliating and degrading treatment;

(d) the passing of sentences and the carrying out of executions without previous judgement pronounced by a regularly constituted court, affording all the judicial guarantees which are recognized as indispensable by civilized peoples.

2. The wounded and sick shall be collected and cared for.

An impartial humanitarian body, such as the International Committee of the Red Cross, may offer its services to the Parties to the conflict.

The Parties to the conflict should further endeavor to bring into force, by means of special agreements, all or part of the other provisions of the present Convention.

The application of the preceding provisions shall not affect the legal status of the Parties to the conflict.