The Law of Armed Conflict (LOAC), or International Humanitarian Law (IHL) as it is sometimes referred to (we will use LOAC throughout this page), is a unique branch of international law which governs the conduct in hostilities. The term “hostilities” is another term for “war” or “armed conflict.”
As it’s titles indicate, the LOAC seeks to strike a balance between the desires of a state. The state’s desires are (1) to achieve the state’s goal of defeating the enemy and (2) the need to mitigate the suffering of war as much as possible. The LOAC does not address the legality of the war (jus ad bellum) but only the conduct in hostilities (jus in bello).
The LOAC consists of both treaty and customary international law. The primary treaties include the Geneva Conventions and The Hague Convention. Customary International Law is made up of the practices of Nations. In other words, when the actions taken by states are so common and accepted that they rise to the point where other states feel as if they are legally obliged to act in the same manner, then those actions are considered to be Customary International Law (i.e. the actions required to be taken by a state are not written law but are instead considered mandatory due to customary practice).