What is international humanitarian law?

International humanitarian law (IHL) is a set of rules that seeks, for humanitarian reasons, to limit the effects of armed conflict. It protects persons who are not, or are no longer, directly or actively participating in hostilities, and imposes limits on the means and methods of warfare. IHL is also known as "the law of war" or "the law of armed conflict". IHL is part of public international law, which is made up primarily of treaties, customary international law and general principles of law (see Article 38 of the Statute of the International Court of Justice). A distinction must be made between IHL, which regulates the conduct of parties engaged in an armed conflict (jus in bello), and public international law, as set out in the Charter of the United Nations, which regulates whether a state may lawfully resort to armed force against another state (jus ad bellum). The Charter prohibits such use of force with two exceptions: cases of self-defence against an armed attack, and when the use of armed force is authorized by the United Nations Security Council. IHL does not stipulate whether the commencement of an armed conflict was legitimate or not, but rather seeks to regulate the behaviour of parties once it has started.