Some Reflections on the 'Incidental Harm' Side of Proportionality Assessments.

• Author: Gillard, Emanuela-Chiara
• Position: Special Issue: The Law of Armed Conflict

TABLE OF CONTENTS I. INTRODUCTION 827 II. APPLYING THE SAME YARDSTICK TO BOTH SIDES 828 OF THE ASSESSMENT III. THE TYPES OF HARM OR DAMAGE THAT FALL 830 WITHIN THE PROPORTIONALITY ASSESSMENT IV. "REVERBERATING" OR "KNOCK-ON" EFFECTS 831 V. NEXT STEPS 833 I. INTRODUCTION

The prohibition of attacks expected to cause incidental loss of civilian life, injury to civilians, or damage to civilian objects that would be excessive in relation to the concrete and direct military advantage anticipated lies at the heart of the rules of international humanitarian law (IHL) regulating the conduct of hostilities. According to Article 51(5)(b) of the First Additional Protocol of 1977 to the Geneva Conventions of 1949 (AP I), a disproportionate attack is an attack that may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof that would be excessive in relation to the concrete and direct military advantage anticipated.

Although first codified in Additional Protocol I, the prohibition was already considered a rule of customary law at the time, (1) and there now appears to be general agreement that it constitutes a rule of customary law applicable in international and non-international armed conflicts. (2)

The rule on proportionality represents the most apparent manifestation of the balance between military necessity and considerations of humanity that underpins IHL. As military operations are taking place in densely populated areas with increasing frequency, the rule's significance for the protection of civilians has become even more key. It is of central relevance to the current discussions on the use of explosive weapons in populated areas.

Determining what falls into the two "sides" of the proportionality assessment as clearly as possible is essential to the proper application of the rule in practice. The expected "military advantage side" of the equation has received considerable attention; the "incidental harm side" less so--even though it is equally key in assessing the lawfulness of an attack. It raises a number of legal issues that need to be addressed by belligerents to ensure they are complying with the law. Proportionality is a challenging topic and is frequently misunderstood by nonexperts and the media, particularly while hostilities are unfolding. Addressing the incidental harm side of the assessment would also provide reassurance that this dimension is being given proper consideration.

This Article focuses on just some of the questions covered at the IDF panel, although there are many that warrant closer consideration.

2. APPLYING THE SAME YARDSTICK TO BOTH SIDES OF THE ASSESSMENT

   First, as a preliminary point, the same interpretation of what constitutes an attack must be adopted for both "sides" of the proportionality assessment. Article 49(1) of AP I defines attacks as "acts of violence against the adversary, whether in offence or in defence." (3) There has been considerable discussion of what constitutes an "attack" for determining the expected military advantage in proportionality assessments. There is agreement that it is neither, at one end of the spectrum, one single strike, nor, at the other, a military campaign as a whole. (4) A number of states submitted statements at the time of ratification of AP I indicating their understanding that the military advantage anticipated from an attack is intended to refer to the advantage anticipated from the attack considered as a whole and not only from isolated or particular parts thereof. (5)

   In conducting proportionality assessments, the same interpretation of "attack" must also be adopted for assessing the expected incidental harm. The language of Article 51(5)(b) of AP I does not suggest otherwise, and taking a different approach would undermine the very purpose of the rule.

   Thus, if in assessing the anticipated military advantage it is the "attack as a whole rather than isolated or particular parts of the attack" that must be considered, it is the expected incidental harm from the same attack "as a whole" that must be put on the other side of the scales. This means that it is the immediate incidental harm caused by different elements of the "attack" that must be considered, and that the same timeframe must be adopted for considering relevant harm as for the military advantage.

   By way of example, in the 2006 discussions on explosive remnants of war, it was noted that the use of cluster munitions could lead to a military advantage that materialised in...