International humanitarian law (IHL) is not only based on treaties such as the 1949 Geneva Conventions, but also includes a substantial body of customary (unwritten) rules.
Customary IHL is particularly important in today’s armed conflicts. It fills the gaps left by treaty law, strengthening the protection offered to people affected by armed conflict. For example, many rules of customary IHL apply in non-international armed conflicts and therefore help to supplement the limited treaty law that applies to those situations.
In 2005, the International Red Cross Red Crescent Movement (ICRC) published a study which identified 161 rules of customary IHL and presented the State practice underpinning these rules. Like IHL treaties, the rules of customary IHL address the protection of people who are not or are no longer participating in hostilities. They also restrict the means and methods of warfare. As mentioned above, many of these rules apply in both international and non-international armed conflicts.
Co-operation with the International Red Cross Red Crescent Movement
The original ICRC study on customary IHL covered State and international practice up until the end of 2002. Because the formation of customary law is a dynamic process, the ICRC and the British Red Cross are working together to update the practice contained in the study. In 2010 the rules and the practice underpinning them were made available in a freely accessible online database.
The database on customary IHL is periodically updated with new practice. Source materials are gathered by a network of ICRC delegations and by National Red Cross and Red Crescent Societies around the world.
A research team, based at the Lauterpacht Centre for International Law in Cambridge, analyses these materials and incorporates them into the online database. The team is jointly managed by the ICRC and the British Red Cross.
Visit the ICRC database on customary IHL.