12.3 The Principles of the Laws of Armed Conflict

Distinction: the parties must distinguish between civilians and combatants, and between civilian objects and military objectives, at all times — only military objectives attackable (AP I's test: effective contribution to military action + definite military advantage); the civilians' immunity, with the direct-participation "revolving door" (protection lost while directly participating, recovered on withdrawal); Proportionality: attacks expected to cause incidental civilian harm excessive in relation to the concrete and direct military advantage anticipated are prohibited (AP I's formula) — the commander's ex ante assessment; the feasible-precautions duty (warnings, means-and-methods choice); the "excessive" judgment's tragic arithmetic; Military necessity: the measures not forbidden by IHL and necessary for the legitimate military purpose — necessity as limiting, not licensing: no wanton destruction; the commander's necessity can never justify the prohibited (the prohibition's priority over necessity — modern IHL's settled hierarchy); Unnecessary suffering: weapons and methods of a nature to cause superfluous injury or unnecessary suffering prohibited (the expanding bullet's and poison's classic bans; the blinding laser's modern application) — no more harm than the military purpose requires even to lawful combatants; The supporting rules: the humanity principle; the chivalric residue (perfidy's prohibition, ruses' permission); the Martens Clause ("the dictates of public conscience" — Unit 2); the protected zones; and the ICJ's Nuclear Weapons Advisory Opinion (1996): the principles' application confirmed, but the weapon's extreme-circumstance legality…