There is good reason to think that law and war have nothing to do with one another, and this has certainly been so for most of the lifetime of mankind. Cicero's famous observation-silent enim leges inter arma – from which I take my title, was not a novel insight when uttered in 52 B.C. and in any case was not said in the context of war, but of a prosecution for murder in the aftermath of the Roman riots of that era between the partisans of the populares and optimates. Clausewitz, however, said much the same thing when he decried moderation in warfare, and expressed contempt for legal rules:
War is... an act of force to compel an enemy to do our will.... [A]ttached to force are certain, self-imposed, imperceptible limitations hardly worth mentioning, known as international law and custom, but they scarcely weaken it. Force – that is, physical force, for moral force has no existence save as expressed in the state and its law – is thus the means of war.
This view of law and war as mutually exclusive has prevailed through most of the various periods in the life of the modem state.
Law | Military, War, and Peace
Philip C. Bobbitt,
Inter Arma Enim Non Silent Leges,
Suffolk U. L. Rev.
Available at: https://scholarship.law.columbia.edu/faculty_scholarship/3167