The Third Geneva Convention establishes a detailed (and therefore strict) definition of who can be considered a prisoner of war and who enjoys this status. This definition is broader than the definition of combatants in the strict sense (CGIII Art. 4.1, 4.5). Combatants in international armed conflicts include members of the regular armed forces, members of volunteer militias and resistance forces who meet certain criteria, members of the armed forces of a State not recognized by the Detaining Power, and civilians who form a mass survey (other contributions to this symposium deal here and here with legal issues relevant to these categories). Combatants enjoy important privileges under the law of armed conflict, including prisoner-of-war status if captured and immunity of combatants from national prosecution for lawful acts of war committed in wartime. However, these privileges are just that – privileges that can be lost if a fighter does not fulfill the required obligations of legal combatant status. The incidents reported during the fighting in Ukraine in the early days of the conflict highlighted both sides of this balance: the essential protection of combatants and the consequences of non-compliance. With regard to unlawful combatants, the Israeli Supreme Court ruled that the categories of combatant and civilian were mutually exclusive and that there was no third category, which would concern unlawful combatants. The court concluded that the terrorists belonged to the category of civilians participating in hostilities. ▸ Civilians ▸ Terrorism Sometimes civilians can participate in hostilities without formal membership in a regular force. This can occur especially in connection with spontaneous uprisings in the occupied territories. This can also occur in other armed conflicts where the distinction between civilians and combatants becomes more difficult.
In such cases, civilians taking a direct part in hostilities temporarily lose the protection provided for civilians, but only for the duration of their participation in hostilities (Article 51.3, Article 13.3 of the APII). In this case, if captured, they may obtain the status of prisoners of war (article 45 of the IPA). Without specifying the conditions or circumstances, Additional Protocol I provides for the protection of persons taking part in hostilities. It stipulates that persons involved in the conflict who have fallen into the hands of the enemy are considered prisoners of war and are therefore protected by the Third Convention (IPA, Art. 45.1). This clause prevents individuals from being denied both civilian and combatant status, and thus excluded from all protection measures under humanitarian law. Article 45.1 complements the rights of the inhabitants of an unoccupied territory who spontaneously take up arms when the enemy approaches to resist the invading forces. In such situations, these residents obtain prisoner-of-war status if captured (CGIII art. 4.A.6). This chapter focuses on the distinction between civilians and combatants, a cornerstone of international humanitarian law. The 1977 Additional Protocols stipulate that warring parties must distinguish between civilian populations and civilian objects of combatants and military targets.
The Geneva Conventions and two Additional Protocols define different situations and types of persons covered by their definition. In general, a civilian is defined as a person who is not directly involved in military actions or hostilities or who belongs to the armed forces. The conventions dispense with a definitive definition to exclude certain civilians who fall into the categories. Article 4 of Geneva Convention III defines combatants more clearly as members of the armed forces of a Party to the conflict, including members of militias or volunteer corps forming part of those forces. International humanitarian law defines who is a civilian, but not what constitutes a civilian object. To know them, it is necessary to refer to article 52 (2) of Additional Protocol I, which specifies exactly what these military objectives are. In case of doubt as to the status of a person who does not fall within one of the categories of combatants within the meaning of the Geneva Conventions and their Additional Protocols, he or she must be considered a civilian (CPR art. 50). Additional Protocol I stipulates that «any combatant who falls into the hands of an adverse Party shall have the status of prisoner of war» (IPA Article 44.1). In addition to the right to take part in hostilities, combatants are entitled to prisoner-of-war status if captured during an international armed conflict.  «While all combatants are bound to respect the rules of international law applicable in armed conflict, violations of those rules do not deprive a combatant of his right to be a combatant or, if he falls into the power of an opposing party, of his right to be a prisoner of war.»  In the context of an internal armed conflict, humanitarian law does not use the term combatant because it is difficult to clearly determine who is a member of the national armed forces and who is a member of an organized opposition group.
Therefore, it would be difficult to define who is legitimate in the use of force. In such situations, humanitarian law makes a clear distinction between those who take part in hostilities and those who are not. Both categories of persons shall, depending on the circumstances, enjoy the protection to which they are entitled as combatants, prisoners of war, conflict-related detainees, wounded and sick or civilians. Most disadvantaged combatants who are not entitled to protection under the Third Geneva Convention do so under the Fourth Geneva Convention (IVAG), which affects civilians until they have received a «fair and just trial.» If found guilty after an ordinary trial, they may be punished under the civil law of the Detaining Power. An enemy combatant can be defined as a person who conducts hostilities for the other party during armed conflict. ▸ Attacks ▸ Children ▸ Civilians ▸ Detention ▸ Duty of commanders ▸ Espionage ▸ Fundamental guarantees ▸ Ill-treatment ▸ Insurgents ▸ Mercenaries ▸ Methods (and means) of war ▸ Non-combatants ▸ Prisoners of war ▸ Resistance movement ▸ Responsibility ▸ Situations and persons not expressly covered by humanitarian law ▸ Special agreements ▸ Terrorism ▸ War ▸ War crimes/crimes against humanity Taking into account the development of armed conflicts and In 2010, the ICRC published an Interpretative Guide on the concept of direct participation in hostilities in IHL.