What is international humanitarian law (IHL)?
International humanitarian law (IHL) is the part of international law that applies during an armed conflict (a war). It is also called the law of war or the law of armed conflict. Its idea is simple: war has limits.
- Who it protects: people who take no part in the fighting, and fighters who can no longer fight (wounded, sick, captured).
- What it limits: the means (weapons) and methods (ways of fighting) that can be used.
- Who must obey: all sides, equally. It does not matter who started the war or who is right.
IHL does not say whether going to war is legal. That is a different question, answered by the UN Charter. IHL only governs how a war is fought.
IHL and human rights. Human rights law protects all people at all times, in peace and in war. In a war some rights can be limited in an emergency (for example, free movement), but others can never be broken, such as the bans on torture, slavery and killing prisoners. IHL is the more detailed law for war; human rights law keeps working beside it.
Where do the rules come from?
IHL grew from old customs of fair fighting. It became written law in modern times:
- 1864: the first Geneva Convention on caring for wounded soldiers, after the founders of the Red Cross movement saw the suffering of a battle.
- 1899 and 1907: the Hague Conventions on methods of warfare.
- 1949: the four Geneva Conventions: (1) wounded and sick soldiers on land, (2) wounded, sick and shipwrecked at sea, (3) prisoners of war, (4) civilians.
- 1977: two Additional Protocols with more detail on civilians and on internal wars (the 1949 Conventions are accepted by almost every state).
Many IHL rules are also custom, so they bind states even if a treaty was not signed. Rules that apply to international wars (between states) and to non-international wars (civil wars) are not exactly the same, but the basic protections apply in both.
The main rules: distinction, proportionality, precaution
Five ideas sit behind most rules:
- Distinction: always tell apart fighters and military targets (can be attacked) from civilians and civilian objects (homes, schools, shops, farms, water supply), which must never be the target. Attacks that cannot aim at a target, and attacks meant to spread terror among civilians, are forbidden.
- Proportionality: an attack on a legal target is forbidden if the expected harm to civilians would be excessive compared with the clear military gain.
- Precaution: commanders must take every practical step to avoid or reduce harm to civilians: check the target, choose the right weapon and warn people where possible.
- Military necessity: force may be used only for a real military aim, not for revenge or to spread fear.
- Humanity: do not cause unnecessary suffering, and treat everyone humanely.
Applying IHL: states must teach the rules to their armed forces, make them part of national law, and punish breaches. Commanders are responsible for what their soldiers do. A soldier must refuse an order that is clearly a war crime; "I was only following orders" is not a full defence.
Protected persons and emblems
Protected persons must be respected and treated humanely, with no difference based on race, religion, sex or opinion:
- Civilians: must not be attacked, taken as shields or forced to leave without a strong reason. Their food, water and homes must be spared.
- Wounded and sick (also enemy fighters): must be collected and cared for.
- Prisoners of war and detainees: must be treated humanely, given food and medical care, kept safe from insults and violence, and may give only basic information about themselves. They must be released when the war ends.
- Medical and religious staff, and humanitarian workers: must be allowed to do their work and must not be attacked. Children and women get extra protection, and children must not be sent to fight.
Emblems show protected status: the red cross, the red crescent and the red crystal, each on a white background. Used as a protective sign, they cover hospitals, ambulances and medical staff. Using them to trick the enemy is perfidy, a war crime. Other protective signs include the white flag (a request to talk or surrender) and the special sign for cultural property.
Means and methods of warfare (overview)
The right of the parties to choose their weapons is not unlimited.
- Banned or limited weapons: weapons that cause needless suffering or cannot tell civilians from fighters. Treaties limit or ban poison gas and chemical and biological weapons, blinding laser weapons, anti-personnel mines (for states that joined the treaty), cluster munitions (for states that joined) and weapons using undetectable fragments.
- Banned methods: attacks on civilians, starving civilians as a method of war, hostage-taking, using human shields, pretending to be a protected person (perfidy) and destroying the natural environment on a large scale.
- Cultural property (museums, places of worship, heritage sites) must be spared.
- New weapons: every state must check that a new weapon or technology (for example cyber tools or drones) obeys IHL before using it.
Breaking these rules seriously is a war crime. States must search for and try the suspects, and the International Criminal Court can try individuals when states do not.
Personal safety and helping in conflict
IHL also gives ordinary people a few clear ideas for safety. Follow official warnings from your local authorities and the Red Cross, and move to a safe place when told. Do not touch unknown objects such as unexploded shells or mines; stay away and tell the authorities. Do not enter a fenced military area. Help the wounded only if it is safe, and call trained helpers. Never use a protective emblem without permission: it can put real helpers in danger.
This page is general learning, not training. In a real emergency follow your local authorities and trained rescuers.
Key formulas and definitions
- IHL = law that limits the harm of war (also called law of armed conflict)
- Core rules: distinction, proportionality, precaution, necessity, humanity
- Four Geneva Conventions (1949): wounded on land; wounded at sea; prisoners; civilians
- Emblems: red cross, red crescent, red crystal on white
- Attack is forbidden if civilian harm is excessive compared with the military gain
- IHL binds all sides equally
Worked examples
1. A fighting force uses a factory that makes military vehicles. Can it be a target? What if a school stands next door?
The factory is a military target. The school is a civilian object and must be spared. Attacking the factory is lawful only if the harm to the school and nearby people is not excessive compared with the military gain, and the attacker takes every practical step to reduce that harm (precaution).
2. A soldier captures an enemy soldier. List three things the captor must do.
Treat the prisoner humanely (no violence, insults or torture), give food, water and medical care, and keep the prisoner safe. The prisoner must be released when the war ends.
3. A group paints a red cross on a truck that carries weapons so it will not be attacked. Is this allowed?
No. This is perfidy, using a protective emblem to trick the other side. It is a war crime and also puts real medical vehicles at risk.
4. Which law protects a prisoner from being tortured: IHL, human rights law or both?
Both. IHL (Geneva Conventions) and human rights law forbid torture, and this ban can never be set aside, even in war.
Common mistakes
- Thinking IHL decides whether a war is legal. It only covers how a war is fought; the UN Charter covers when force is allowed.
- Thinking only the 'good' side must follow the rules. IHL binds all sides equally, whoever started the war.
- Thinking enemy fighters have no rights. Wounded, sick and captured fighters are protected.
- Mixing up IHL and human rights law. IHL applies only in armed conflict; human rights law applies always, and both apply in war.