Since 1864, the International Humanitarian Law has developed its own general principles of law, which also constitute – according to the Art. 38 of Statute of International Court of Justice (ICJ) – sources of law. This approach was confirmed in the jurisprudence of ICJ and International Tribunal for Former Yugoslavia.
The first – principle of humanity, a core for all human relations, requires that every human being has the capacity and ability to show respect for all, even enemies. The principle of humanity is complemented by Martens clause, which demands elementary considerations of humanity in armed conflicts. The civilian population and combatants are not only protected by specific rules of humanitarian law but also by international law. The protection derives from international custom and principle of humanity.
The principle of distinction plays a pivotal role in the humanitarian law, as it requires a distinction between civilians and combatants as well as civilian and military objectives. The whole International Humanitarian law is based on this principle and it is illuminated in all Geneva Conventions and Additional Protocols.
Principles of necessity and proportionality must be read together with the principle of distinction. During an armed conflict, it is always difficult to target only military objectives combatants and specific infrastructure, if not say it is impossible. Civilians are often – whether they want or not – part of armed conflicts. In modern conflicts, they are directly exposed to the danger caused by armed conflicts. It is therefore absolutely demanded that any military actions be proportionate and necessary in order to accomplish foreseen objectives. The principle prohibits from causing unnecessary suffering.
Most of these essential principles have been codified by international humanitarian treaties or were evoked by international tribunals and are considered as the customary international law applicable during armed conflicts.