Just War Theory and the Laws of War as Nonidentical Twins

Abstract: This essay examines the similarities, but even more the dissimilarities, between (nonrevisionist) just war theory and the laws of war. The similarities are obvious: both just war theory and the laws of war distinguish jus ad bellum from jus in bello, and incorporate the principles of distinction, proportionality, and necessity. The dissimilarities derive from the special character of law. Law needs binary, yes-no standards for drawing lines, for example between armed conflict and lesser forms of violence. Laws come in packages (regimes), so that changing only one law is not always practicable. And legal propositions, unlike philosophical propositions, are often detachable from their reasons and applied in unexpected and unwelcome ways. This is especially important in the stresses of battle, when rules of warfare must be usable “off the shelf” by middle- or lower-ranked personnel with no opportunity for bespoke deliberation. The essay provides contemporary illustrations of these differences.

Keywords: Additional Protocol II; armed conflict; belligerent occupation; just war theory; law of war; Tadić test; international humanitarian law; Geneva conventions; jus in bello; jus ad bellum

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