International Humanitarian Law

What It Is

International humanitarian law governs how wars may be fought, not whether they may be fought (that question belongs to jus ad bellum and the UN Charter). It applies once an armed conflict exists, binding all parties — states and, in non-international conflicts, organised armed groups. Its purpose is humanitarian: to limit suffering by protecting civilians, the wounded, prisoners of war, and medical and aid workers, and by restricting the means and methods of warfare.

Core Sources

The backbone of IHL is the four Geneva Conventions of 1949 and their Additional Protocols of 1977 and 2005, which protect the wounded and sick, shipwrecked forces, prisoners of war, and civilians. The older Hague Conventions (1899 and 1907) regulate the means and methods of warfare. Alongside treaty law sits a large body of customary international humanitarian law, binding even on states that have not ratified specific treaties.

Core Principles

Four principles run through all of IHL:

• Distinction — parties must always distinguish between combatants and civilians, and between military objectives and civilian objects, and direct attacks only at the former.
• Proportionality — an attack expected to cause civilian harm excessive in relation to the concrete military advantage is prohibited.
• Precaution — parties must take all feasible precautions to spare civilians.
• Humanity — it is forbidden to inflict suffering or destruction not necessary for a legitimate military purpose.

These underpin specific rules on the protection of civilians and prohibited weapons.

IHL vs Human Rights Law

IHL and international human rights law overlap but differ: human rights law applies at all times, while IHL is the specialised regime (lex specialis) that governs situations of armed conflict. In wartime the two operate together, with IHL providing the more specific rules.

Enforcement

IHL is enforced through national prosecutions, the International Criminal Court (for war crimes, under the Rome Statute), ad hoc tribunals, and universal jurisdiction. The International Committee of the Red Cross (ICRC) holds a special mandate as guardian of IHL, visiting detainees, assisting victims, and promoting the law. Grave breaches of the Geneva Conventions are war crimes that all states have a duty to repress.