Revisiting ad bellum Proportionality: Challenging the Factors Used to Assess It

Traditionally, international law has established a binary distinction between jus ad bellum and jus in bello. The former relates to the right to exercise military force. The latter regulates the conduct of adversaries engaged in an armed conflict. However, the prevailing legal approach doesn't accept this dichotomy. It wants to reduce war's hazards by applying the ad bellum rules, including the proportionality requirement, continuously throughout the conduct of armed conflict. To that end, it has established factors that define the essence of the continuing ad bellum proportionality requirement. This article challenges the near-unanimous consensus regarding these factors. It argues that their strict application is not normatively desirable and might be counter-effective in light of the proportionality requirement's de-escalation rationale. It further suggests replacing the micro constraining factors with a macro standard, constraining the use of force, throughout the armed conflict, to the minimum required to achieve a lawful war aim.