Diakonia - People change the world

Basic principles of IHL

Rules of international humanitarian law (IHL) attempt in broad terms to regulate conflict in order to minimise human suffering. IHL reflects this constant balance between the military necessity arising in a state of war and the needs for humanitarian protection.


International Humanitarian Law is founded upon the following principles:

distinction between civilians and combatants

prohibition of attacks against those hors de combat

prohibition on the infliction of unnecessary suffering

principle of proportionality

notion of necessity

principle of humanity

Each basic principle should be found within the specific rules and norms of IHL itself, but the principles may also help interpretation of the law when the legal issues are unclear or controversial. Depending on the issue, the balance between the principles and interest shifts. For example, during hostilities, military necessity may limit the notion of humanity by allowing for destruction, but in other situations such as the protection of the wounded and sick, the principle of humanity is at the heart of the legal rules.

The principle of distinction between civilians and combatants

The principle of distinction underpinning many rules of IHL is that only fighters may be directly targeted. This is a necessary compromise that IHL provides for in order to protect civilians in armed conflict. Without the principle of distinction, they would be no limitation on the methods of warfare.

The specific rules where the principle of distinction is set out concerns Article 48 and 52  of Additional Protocal 1 to the Geneva Conventions. This defines who is a combatant and a military object that can be lawfully attacked. Any direct attack against a civilian or civilian object is not only a violation of IHL but also a grave breach. Direct attacks against civilians and/or civilians objects are categorised as war crimes. Additionally, any weapon which is incapable of distinguishing between civilians/civilian objects and fighters/military objects is also prohibited under IHL. The principle is also a rule of customary international law, binding on all states.

The prohibition of attacks against those hors de combat

The prohibition to attack any person hors de combat (those who are sick and wounded, prisoners of war) is a fundamental rule under IHL. For example, while a solider could be targeted lawfully under normal circumstances, if that soldiers surrenders or is wounded and no longer poses a threat, then it is prohibited to attack that person. Additionally, they may be entitled to extensive protections if they meet the criteria of being a Prisoner of War.

The prohibition on the infliction of unnecessary suffering

While IHL does permit violence, it prohibits the infliction of unnecessary suffering and superfluous injury. While the meaning of such terms is unclear and the protection may as such be limited, even fighters who may be lawfully attacked, are provided protection by this prohibition. One rule that has been established based on this principle is the prohibition on the use of blinding laser weapons.

The principle of proportionality

The principle of proportionality limits and protects potential harm to civilians by demanding that the least amount of harm is caused to civilians, and when harm to civilians must occur it needs be proportional to the military advantage. The article where proportionality is most prevalent is in Article 51(5) (b) of API concerning the conduct of hostilities which prohibits attacks when the civilian harm would be excessive in relation to the military advantage sought. This is an area of hostilities where we often hear the term ‘collateral damage’.

The principle cannot be applied to override specific protections, or create exceptions to rules where the text itself does not provide for one. As with the principle of necessity, the principle of proportionality itself is to be found within the rules of IHL themselves. For example, direct attacks against civilians are prohibited and hence a proportionality assessment is not a relevant legal assessment as any direct attack against even a single civilian who is not taking part in hostilities is a clear violation of IHL. Proportionality is only applied when a strike is made against a lawful military target.

Click here to read more about the basic principles of the conduct of hostilities.

The notion of necessity

A dominant notion within the framework of IHL is military necessity, often the principle which clashes most with humanitarian protection. Military necessity permits armed forces to engage in conduct that will result in destruction and harm being inflicted. The concept of military necessity acknowledges that under the laws of war, winning the war or battle is a legitimate consideration.

However the concept of military necessity does not give the armed forces the freedom to ignore humanitarian considerations altogether and do what they want. It must be interpreted in the context of specific prohibitions and in accordance with the other principles of IHL.

 It is important to note that the notion itself is to be found within the rules of IHL. For example, Article 52 of Addition Protocol I lists those objects that can be subject to lawful attacks. The notion cannot be applied to override specific protections, or create exceptions to rules where the text itself does not provide for one.

Click here to read more about ‘military necessity’.

The principle of humanity

The principle of humanity, and its absence during the battle of Solferino of 1859, was the central notion that inspired the founder of the International Committee of the Red Cross (ICRC), Henry Dunant. The principle stipulates that all humans have the capacity and ability to show respect and care for all, even their sworn enemies. The notion of humanity is central to the human condition and separates humans from animals.

IHL, the principles of which can be found in all major religions and cultures, set out only basic protections, but ones which look to demonstrate that even during armed conflict there is some common sense of and respect for humanity. Modern IHL is not naive and accepts that harm, destruction and death can be lawful during armed conflict. IHL simply looks to limit the harm, and the principle of humanity is very much at the heart of this ambition. Many rules of IHL are inspired by this notion, specifically those setting out protections for the wounded and sick.