Lieber Studies Volume 6

Proportionality in International Humanitarian Law

Edited by Michael N. Schmitt & Winston S. Williams

Edited Volume, 280 Pages
ISBN: 9780197556726
Published June 11, 2021

Published by Oxford University Press


Disclaimer: Books in the Lieber Studies Series are not official publications of the United States Military Academy, Department of the Army, or Department of Defense. The views expressed in these volumes represent the authors’ personal views and do not necessarily reflect those of the Department of Defense, the United States Army, the United States Military Academy, or any other department or agency of the United States Government. The analysis presented stems from academic research of publicly available sources, not from protected operational information. 



The principle of proportionality is one of the corner-stones of international humanitarian law. Almost all states involved in armed conflicts recognize that launching an attack which may cause incidental harm to civilians that exceeds the direct military advantage anticipated from the attack is prohibited. This prohibition is included in military manuals, taught in professional courses, and accepted as almost axiomatic. And yet, the exact meaning of the principle is vague. Almost every issue, from the most elementary question of how to compare civilian harm and military advantage, to the obligation to employ accurate but expensive weapons, is disputed. Controversy is especially rife regarding asymmetrical conflicts, in which many modern democracies are involved. How exactly should proportionality be implemented when the enemy is not an army, but a non-state-actor embedded within a civilian population? What does it mean to use precautions in attack, when almost every attack is directed at objects that are used for both military and civilian purposes?

In Proportionality in International Humanitarian Law, Amichai Cohen and David Zlotogorski discuss the philosophical and political background of the principle of proportionality. Offering a fresh and comprehensive look at this key doctrine, they comprehensively discuss the different components of the proportionality “equation” – the meaning of “incidental harm” to civilians; the “military advantage” and the term “excessive”. The book proposes the debates over the principle of proportionality be reframed to focus on the precautions taken before the attack along with the course States should follow in investigations of the violations of the principle.


Table of Contents


Chapter 1: An Introduction to Proportionality
Chapter 2: Ethical and Constitutional Foundations
Chapter 3: A General Overview of Proportionality in IHL

Chapter 4: Military Advantage
Chapter 5: Incidental Harms
Chapter 6: Soldiers vs. Civilians
Chapter 7: Strategic and Cultural Considerations
Chapter 8: Direct Participation in Hostilities and its Effect on Proportionality
Chapter 9: Human Shields and Proportionality
Chapter 10: The Principle of Distinction and its Relation to Proportionality

Chapter 11: The Vagueness of Proportionality
Chapter 12: Procedural Aspects of Proportionality
Chapter 13: Judicial Review and Investigations
Chapter 14: The Future of Proportionality


Volume 6 Masthead