Mixing oil and water? The interaction between jus ad bellum and jus in bello during armed conflicts

Abstract

This article assesses the applicability of jus ad bellum rules during armed conflicts. It first presents the overlap between the jus ad bellum and jus in bello with respect to the use of armed interstate force, then rejects the ‘displacement’ approach, according to which jus ad bellum rules are inapplicable during armed conflicts, arguing for an interaction between the fields based on the facts prevailing before the launching of an attack. Such factual interaction could be determined pursuant to the intensity of the conflict, so that once a certain threshold is reached, the use of interstate force in self-defence is permissible, and jus ad bellum does not place any additional constraints on the attacker. The findings are applied to the alleged attacks by Israel on Syrian territory during the Syrian Civil War, with the author concluding that jus ad bellum fully applies due to the low intensity of the conflict.