ABSTRACT
War must have a just cause. It must also be necessary and a "last resort", in relation to other acceptable means towards achieving its benefits, such as diplomacy. Once other options have been reasonably exhausted, war must be declared by a legitimate authority and fought for the right intentions. International law, like contemporary just war theory, recognizes self-defense and the resistance of armed aggression as the primary justification for war; it does not contain any precise ad bellum proportionality restriction. The most fundamental distinction governing conduct in war separates soldiers from civilians. More precisely, it distinguishes those who actively partake in combat from those who are not directly engaged in it. The legal restriction on excessive force and limitation of proportionality in war adopts the traditional separation between jus ad bellum and jus in bello and applies regardless of the justness of cause.
