Overview of international humanitarian law

International humanitarian law comprises a set of rules, established by treaty or custom, applicable in situations of armed conflict. As noted, it is inspired by considerations of humanity and the mitigation of human suffering.

What are the aims and sources of IHL?

Although the origins of IHL can be traced to at least the nineteenth century, the principles and practices on which it is based are much older. International humanitarian law, also referred to as the law of armed conflict or the law of war, is designed to balance humanitarian concerns and military necessity. It subjects warfare to the rule of law by limiting its destructive effect and mitigating human suffering. IHL covers two key areas:

  • Protection and assistance to those affected by the hostilities
  • Regulation of the means and methods of warfare

The sources of IHL are the same as those for international law in general:

International convention: The two main treaty sources of IHL are the Hague Convention (1907), setting out restrictions on the means and methods of warfare, and the four Geneva Conventions (GCs) (1949), providing protection to certain categories of vulnerable persons. These are the wounded and sick in armed forces in the field (GCI); the wounded, sick and shipwrecked members of armed forces at sea (GCII); prisoners of war (GCIII); and protected civilians (GC IV). The Fourth Geneva Convention is particularly relevant to humanitarian protection and assistance. It was established to prevent in future conflicts the scale of civilian suffering experienced during the two World Wars.

The two branches of law covered in the Hague and Geneva Conventions are further developed by the first two Protocols Additional to the Geneva Conventions on the protection of civilians (1977). These are referred to as Additional Protocol I (AP I), governing international armed conflict, and Additional Protocol II (AP II), governing non-international armed conflict.

The four Geneva Conventions have achieved universal applicability as they have been universally ratified. The Additional Protocols, however, have yet to achieve near-universal acceptance. The United States and several other significant military powers (e.g. Iran, Israel, India and Pakistan) are currently not parties to the protocols.

International custom: A comprehensive study by the International Committee of the Red Cross (ICRC) on IHL and customary law indicates that the majority of rules enshrined in treaty law have received widespread acceptance and have had a far-reaching effect on practice. They thus have the force of customary law. Some provisions in the Hague and Geneva Conventions were reflections of existing customary law, whereas others have developed into customary law. They are therefore binding on all states regardless of ratification, and also on armed opposition groups in the case of non-international armed conflict (Henckaerts, 2005). The application of customary international law is particularly significant for non-international armed conflicts, as treaty law has remained limited in this area.

General principles of law: IHL recognises a number of jus cogens norms, from which no derogation is allowed, for example, prohibitions against genocide and torture.

Judicial decisions and the teachings of the most highly qualified publicists as subsidiary sources: International courts have played a role in interpreting and developing IHL (examples are provided in this guide).

When does IHL apply?

International humanitarian law applies only to situations of armed conflict, but applies to all actors in an armed conflict. IHL distinguishes between international armed conflict and non-international armed conflict; a much more limited range of written rules apply to the latter. Although state practice continues to support this distinction, it has been criticised as arbitrary and impractical, given the nature of current conflicts. However, the law has developed over the years to provide greater coverage of internal armed conflicts. Gaps in the regulation of the conduct of hostilities in AP II regulating non-international armed conflict have largely been filled through customary international law. Gaps remain in the protection framework in the aftermath of conflict. These can result in challenges in humanitarian protection and in the delivery of humanitarian assistance to populations still in need.

International armed conflict: IHL applies to conflicts arising between sovereign states (GCs common Art 2(1)) – including direct conflict between states, and situations in which a foreign power sends troops into a territory to support a local movement – and to situations of partial or total occupation (GCs common Art 2(2)). Additional Protocol I extends the field of application to ‘armed conflicts in which peoples are fighting against colonial domination and alien occupation and against racist regimes in the exercise of their right of self-determination’ (API, Art 1(4)).

Occupation without military presence – Israel and the Gaza Strip

The Geneva Conventions apply to any territory occupied during international armed conflict (Common article 2). Article 42 of the Hague Convention specifies that a ‘territory is considered occupied when it is actually placed under the authority of the hostile army. The occupation extends only to the territory where such authority has been established and can be exercised.’ As such, IHL relevant to occupied territories is applicable when a territory comes under the effective control of hostile armed forces. It can, however, be difficult in practice to identify and confirm such situations. Although Israel withdrew its military forces from the Gaza Strip in 2005, this physical withdrawal of forces was not considered enough to terminate Israel’s ‘effective control’ of the territory, characteristic of occupation. This was attributed to various factors, such as the fact that the Disengagement Plan stated that Israel was to continue to exercise control over the borders of the territory and over its air space and coastal region. In addition, Israel maintained the advantage of being able to enter Palestinian territory at any time to maintain public order. The UN Secretary General thus concluded that it is possible to remain an occupying power, with consequent obligations, without a military presence on the ground (Vité, 2009).

Non-international armed conflict (NIAC): Article 3 common to the GCs applies in the case of ‘armed conflict not of an international character’, whether between a state and a non-state armed group or between non-state armed groups.

In order to be classified as a NIAC – and not a case of ‘internal disturbances and tensions, such as riots, isolated and sporadic acts of violence’ (GC common Article 3, APII Art 1) – such that Article 3 and APII are applicable, the International Criminal Tribunal for the Former-Yugoslavia has indicated that two factual criteria must be satisfied:

  • The violence must reach a certain level of intensity that distinguishes it from situations of internal disturbances such as riots and isolated acts of violence
  • The parties involved must demonstrate a certain level of organisation.

For the first criteria, factors to consider include the collective nature of the fighting and resort to armed force by the state, the duration of the conflict, the nature of the weapons, the frequency of attacks and the number of victims. For the second criteria, it is assumed that government forces automatically fulfil the requirement. As for non-state armed groups, elements to consider include the existence of a command structure and/or internal rules, and the ability to recruit and train new combatants (Vité, 2009).

Article 1 of AP II affirmed these criteria but set a higher threshold to fulfil the criteria of parties involved, adding that these groups should be able to control part of a territory. It also restricts its application to conflicts between a state and a non-state armed group. This is likely to result in many armed conflicts being covered by Common Article 3 but not AP II (Vité, 2009).

What are key provisions and principles of IHL applicable to civilian protection?

The Fourth Geneva Convention focuses on the civilian population. The two additional protocols adopted in 1977 extend and strengthen civilian protection in international (AP I) and non-international (AP II) armed conflict, for example by introducing the prohibition of direct attacks against civilians. A ‘civilian’ is defined as ‘any person not belonging to the armed forces’, including non-nationals and refugees (AP I, Art 50(1)).

IHL provisions and principles protecting civilians

  • The principle of distinction protects civilian persons and civilian objects from the effects of military operations. It requires parties to an armed conflict to distinguish at all times and under all circumstances between combatants and military objectives on the one hand and civilians and civilian objects on the other – and to only target the former. It also requires that civilians lose such protection should they take a direct part in hostilities (AP I, Arts 48, 51-52, 57; AP II, 13-16). The principle of distinction has also been found by the ICRC to be reflected in state practice and thus an established norm of customary international law in both international and non-international armed conflicts (ICRC, 2005b, vol. 1).
  • Necessity and proportionality are established principles introduced in humanitarian law. Under IHL, a belligerent can apply only the amount and kind of force necessary to defeat the enemy. Further, attacks on military objects must not cause loss of civilian life considered excessive in relation to the direct military advantage anticipated (AP I, Arts 35, 51(5)). Every feasible precaution must be taken by commanders to avoid civilian causalities (AP 1, Arts 57, 58). The ICRC has also found the principle of proportionality to form part of customary international law in international and non-international armed conflicts (ICRC, 2005b, vol. 1).
  • The principle of humane treatment requires that civilians are treated humanely at all times (GCIV, Art 27). Common Article 3 of the GCs prohibits violence to life and person (including cruel treatment and torture), the taking of hostages, humiliating and degrading treatment, and execution without regular trial against non-combatants, including persons hors de combat (wounded, sick and shipwrecked). Civilians are entitled to respect for their physical and mental integrity, their honour, family rights, religious convictions and practices, and their manners and customs (API, Art 75(1)). This principle of humane treatment has been affirmed by the ICRC as a norm of customary international law applicable in both international and non-international armed conflicts (ICRC, 2005b, vol. 1).

  • The principle of non-discrimination is a core principle of IHL. Adverse distinction based on race, nationality, religious belief or political opinion is prohibited in the treatment of prisoners of war (GCIII, Art 16), civilians (GCIV, Art 13, common Article 3) and persons hors de combat (common Article 3). All protected persons shall be treated with the same consideration by parties to the conflict, without distinction based on race, religion, sex or political opinion (common article 3, GCIV, Art 27). Each and every person affected by armed conflict is entitled to his/her fundamental rights and guarantees, without discrimination (API, Art 75(1)). The prohibition against adverse distinction is considered by the ICRC as part of customary international law in international and non-international armed conflict (ICRC, 2005b, vol. 1).

  • Women and children are granted preferential treatment, respect and protection. Women must be protected from rape or any form of indecent assault. Children under the age of 18 must not be allowed to take part in hostilities (GCIV, Arts 24, 27; API, Arts 76-78; APII, Art 4(3)).

IHL provisions relevant to humanitarian assistance are discussed in Humanitarian Principles and Humanitarian Assistance.

How is gender and culture treated in IHL?


IHL emphasises in various provisions in the GCs and APs the concept of formal equality and non-discrimination: protections should be provided ‘without any adverse distinction founded on sex’. For example, with regard to female prisoners of war, women are required to receive treatment ‘as favourable as that granted to men’ (GCIII, Arts 14, 16). In addition to claims of formal equality, IHL mandates special protections to women, for example providing female prisoners of war with separate dormitories from men (GCIII, Art 25); and prohibiting sexual violence against women (GCIV, Art27; API, Art 76(2); APII, Art 4(2)).

However, the reality of women’s and men’s lived experiences of conflict has highlighted some of the gender limitations of IHL. Feminist critics have challenged IHL’s focus on male combatants and its relegation of women to the status of victims or granting them legitimacy solely as child-rearers: a study of the 42 provisions relating to women within the Geneva Conventions and the Additional Protocols found that almost half address women who are expectant or nursing mothers (Gardam and Jarvis, cited in Durham and O’Bryne, 2010). Others have argued that the issue of sexual violence against men in conflict has not yet received the attention it deserves (Lewis, cited in Durham and O’Bryne, 2010).

Applying a gender perspective to interpretations of IHL is important so as to consider the diverse experiences of both women and men in conflict situations. This can help to avoid the assumption, along with other forms of stereotyping, that women are mostly ‘victims’ and ‘losers’ in conflict and that men are always the ‘aggressors’ or ‘winners’.

‘Soft law’ has been relied on to supplement the protection of women in armed conflict. This includes: UN Security Council Resolutions 1888 and 1889 (2009), which aim to enhance the protection of women and children against sexual violations in armed conflict; and Resolution 1325, which aims to improve the participation of women in post-conflict peacebuilding. Read together with other legal mechanisms, in particular the UN Convention for the Elimination of All Forms of Discrimination against Women (CEDAW), these can enhance interpretation and implementation of IHL. In addition, international criminal tribunals (e.g. the International Criminal Tribunals for the former Yugoslavia and Rwanda) and mixed tribunals (e.g. the Special Court for Sierra Leone) have contributed to expanding the scope of definitions of sexual violence and rape in conflict. They have effectively prosecuted sexual and gender-based crimes committed during armed conflict: there is now well-established jurisprudence on gender-based crimes. Nonetheless, there remains an urgent need to further develop constructions of gender within international humanitarian law (see Barrow, 2010).


IHL has generally not been subject to the same debates and criticisms of ‘cultural relativism’ as international human rights. Although the modern codification of IHL in the Geneva Conventions and the Additional Protocols are relatively new and European in name, the core concepts are not new and laws relating to warfare can be found in all cultures. ICRC studies (on the Middle East, Somalia, Latin America, and the Pacific, for example) have found that there are traditional and long-standing practices in various cultures that preceded, but are generally consistent with, modern IHL. It is important to respect local and cultural practices that are in line with IHL. Relying on these links and on local practices can help to promote awareness of and adherence to IHL principles among local groups and communities.

Durham (2008) cautions, however, that although traditional practices and IHL legal norms are largely compatible, it is important not to assume perfect alignment: there are areas in which legal norms and cultural practices clash. For example, violence against women is frequently legitimised by arguments of culture, yet is prohibited in IHL and other international law. In such cases, it is important to ensure that IHL is not negatively affected.