INTERNATIONAL EXPERT MEETING 22–23 JUNE 2016 – QUEBEC THE PRINCIPLE OF PROPORTIONALITY IN THE RULES GOVERNING THE CONDUCT OF HOSTILITIES UNDER INTERNATIONAL HUMANITARIAN LAW REPORT This meeting was supported by the Social Sciences and Humanities Research Council of Canada INTERNATIONAL EXPERT MEETING 22–23 JUNE 2016 – QUEBEC THE PRINCIPLE OF PROPORTIONALITY IN THE RULES GOVERNING THE CONDUCT OF HOSTILITIES UNDER INTERNATIONAL HUMANITARIAN LAW Report prepared and edited by Laurent Gisel Legal adviser, ICRC TABLE OF CONTENTS FOREWORD ..................................................................................................................................... 5 ACKNOWLEDGMENTS ..................................................................................................................... 7 INTRODUCTION ............................................................................................................................... 8 The principle of proportionality ........................................................................................................................................... 8 Challenges in the application of the principle of proportionality ............................................................................ 8 Purpose of the meeting and scope of the discussions ................................................................................................... 9 The importance of policies for the protection of civilians during armed conflicts .........................................10 Background document, agenda of the meeting and structure of the report ......................................................10 PART I: MILITARY ADVANTAGE ......................................................................................................11 Session 1: Defining the relevant advantage for the principle of proportionality: concrete, direct and military ..................................................................................................11 a) Background information ..................................................................................................................................................... 11 b) Experts’ comments and discussion ................................................................................................................................15 Session 2: Relevance of force protection and protection of civilians considerations for the principle of proportionality ........................................................................................ 23 a) Background information .................................................................................................................................................... 23 b) Experts’ comments and discussion ............................................................................................................................... 25 PART II: INCIDENTAL HARM .......................................................................................................... 32 Session 3: Relevant types of incidental harm .........................................................................................32 Background information ......................................................................................................................................................... 32 A. Illness and mental harm .................................................................................................................... 33 a) Background information .....................................................................................................................................................33 b) Experts’ comments and discussion ............................................................................................................................... 35 B. Harm to civilian use of ‘dual-use objects’ ......................................................................................... 37 a) Background information .................................................................................................................................................... 37 b) Experts’ comments and discussion ...............................................................................................................................38 C. Economic losses and displacement .................................................................................................... 41 a) Background information .....................................................................................................................................................41 b) Experts’ comments and discussion ...............................................................................................................................42 Session 4: Reverberating effects.............................................................................................................43 a) Background information ....................................................................................................................................................43 b) Experts’ comments and discussion ...............................................................................................................................46 PART III: THE REASONABLE MILITARY COMMANDER ASSESSMENT OF EXCESSIVENESS .......... 52 a) Background information ....................................................................................................................................................52 b) Experts’ comments and discussion ............................................................................................................................... 57 I. The reasonable military commander standard ........................................................................................................ 57 II. Contextual factors .......................................................................................................................................................60 III. Assessing excessiveness ..............................................................................................................................................62 ANNEX 1: LIST OF PARTICIPANTS ................................................................................................. 66 ANNEX 2: AGENDA ........................................................................................................................ 68 THE PRINCIPLE OF PROPORTIONALITY IN THE RULES GOVERNING THE CONDUCT OF HOSTILITIES UNDER IHL 5 FOREWORD Armed conflicts in the 21st century continue to cause tremendous human suffering. Civilians are killed, taken away from their loved ones forever. Some of these killings stem from blatant disregard for international humanitarian law (IHL) by belligerents that directly attack civilians. Others are euphemistically referred to as ‘collateral damage’ and plunge families into mourning. Suffering in war does not depend on whether the conduct giving rise to it was lawful or unlawful, but it is important to clarify when it is unlawful because parties to armed conflicts are required to conduct their military operations in accordance with the law and because compliance with IHL will reduce such suffering. Incidental civilian harm may be lawful or unlawful. It may be lawful – albeit regrettable – where all feasible precautions had been taken to avoid or at least minimize the harm and where this harm was not expected to be excessive compared to the concrete and direct military advantage anticipated. It can only be lawful if these two conditions are fulfilled. Doubts do, however, arise regularly as to whether this has been the case for specific attacks. Determining whether civilian harm caused by a particular attack constitutes a violation of international humanitarian law is rarely a straightforward matter. It is rarely straightforward because the facts known to the commander at the time of the attack are not made public and because the rules governing the conduct of hostilities are formulated in a general and often flexible way to adapt to all situations. These rules encompass and rely on concepts that remain partly undefined and that may therefore be subject to divergent understandings. The object and purpose of the rules governing the conduct of hostilities under international humanitarian law is to protect civilians and civilian objects by establishing an appropriate balance between the principles of military necessity and considerations of humanity. While striking this balance is always difficult, the tension between these complementary, but also competing, principles is possibly nowhere more evident and chal- lenging than in the principle of proportionality. The principle of proportionality prohibits attacks which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated. Put otherwise, it requires belligerents to refrain, due to humanitarian considerations, from attacks against military objectives expected to cause disproportionate incidental civilian harm even if they may be seen as militarily beneficial. The principle of proportionality is relevant in many combat situations and is applied daily by commanders. As fighting increasingly takes place in populated areas, where incidental harm is likely to occur due to the co-location and intermingling