Modern law and modern war:

Warfare has always been a central preoccupation and presented a kind of ultimate test for international law. It is hard to think of international law governing the relations amongst states without having something to say about war – when war is and is not an appropriate exercise of sovereign authority, how war can and cannot be conducted, which of war’s outcomes will and will not become components of a post-war status quo, and so on. It is conventional to imagine that international law restrains war by making distinctions: this is war, and this is not; this is sovereignty, and this is not; this is legal warfare, and this is not. The terms with which these legal distinctions are drawn change over time. The vernacular may be more or less sodden with ethical considerations, more or less rooted in the specific treaty arrangements entered into by states. The distinctions may be drawn more or less sharply, may be matters of kind or degree. What goes on one or the other side of these distinctions may change, but the idea that law is about distinguishing war from peace, sovereign right from sovereign whim, legal from illegal conduct, on the battlefield and off, endures.

Discussions about international law and war usually unfold as if the participants were imagining an international law which would be able to substitute itself for sovereign power in a top-down fashion, first to distinguish legal from illegal violence and then, perhaps not today but eventually, or perhaps not directly but indirectly, to bring that distinction to bear in the life of sovereigns, extinguishing sovereign authority for war at the point it crosses a legal limit. The idea is that the articulation of right will discipline, limit and restrain sovereign power when it turns to violence. International law proposes to bring this about through a series of doctrines, definitions and arguments which say where war begins and ends, and then through an apparatus of institutions and relationships which are linked in one or another way to these doctrines and which are the locus for or the effect of these sayings.