The principle of proportionality prohibits attacks against military objectives which are “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”.
In other words, the principle of proportionality seeks to limit damage caused by military operations by requiring that the effects of the means and methods of warfare used must not be disproportionate to the military advantage sought.




ICRC, The Challenges of Contemporary Armed Conflicts

ICJ, Nuclear Weapons Advisory Opinion (Para. 43)

Israel/Gaza, Operation Cast Lead (Part I, Paras. 120-126, 230-232)

Israel, The Targeted Killings Case (Paras. 40-46)

Israel, Human Rights Committee’s Report on Beit Hanoun (Paras. 38-42)

United States/United Kingdom, Report on the Conduct of the Persian Gulf War

ICTY, The Prosecutor v. Kupreskic et al.(Para. 526)

Federal Republic of Yugoslavia, NATO Intervention (Part A., Paras. 4, 18-19 and Part B., Paras 75-78)

Afghanistan, Drug Dealers as Legitimate Targets

Afghanistan, Goatherd Saved from Attack

Afghanistan, Assessment of ISAF Strategy

Civil War in Nepal (Part II.)

ECHR, Isayeva v. Russia

Georgia/Russia, Human Rights Watch’s Report on the Conflict in South Ossetia (Paras. 28-30, 41-47)

Georgia/Russia, Independent International Fact-Finding Mission on the Conflict in South Ossetia (Paras. 66-67)

Cambodia/Thailand, Border Conflict around the Temple of Preah Vihear

Iran, Victim of Cyber warfare

The armed conflict in Syria

Autonomous Weapon Systems

Libya, NATO Intervention 2011

UN, Report of the Secretary-General for the World Humanitarian Summit

ICRC, International Humanitarian Law and the challenges of contemporary armed conflicts in 2015 (Paras. 155, 160, 168, 179, 294-295)

Israel/Palestine, Operation Protective Edge (Gaza, 13 June - 26 August 2014)

Libya, Report of the Office of the UN High Commissioner for Human Rights (2014/15)

Syria, Report by UN Commission of Inquiry (March 2017)

Afghanistan, Bombing of a Civilian Truck

Italy, Use of force against ambulances in Iraq

Syria, the Battle for Aleppo

ICRC, Statement - War in Cities ; What is at Stake?

Germany, Aerial Drone Attack in Mir Ali/Pakistan

Eastern Ukraine, OHCHR Report on the Situation: November 2016 - February 2017

Central African Republic, No Class: When Armed Groups Use Schools


suggested readings:
BROWN Bernard L., “The Proportionality Principle in the Humanitarian Law of Warfare: Recent Efforts at Codification”, in Cornell International Law Journal, Vol. 10, 1976, pp.134-155.
DINSTEIN Yoram, “Collateral Damage and the Principle of Proportionality”, in WIPPMAN David & EVANGELISTA Matthew (eds), New Wars, New Laws? Applying the Laws of War in 21st Century Conflicts, New York, Transnational Publishers, 2005, pp. 211-224.
FENRICK William J., “The Rule of Proportionality and Protocol I in Conventional Warfare”, in Military Law Review, Vol. 98, 1980, pp. 541-595.
GARDAM Judith, Necessity, Proportionality and the Use of Force by States, Cambridge, CUP, 2004, 259 pp.
GARDAM Judith, “The Proportionality as a Restraint on the Use of Force”, in AYIL, Vol. 20, 1999, pp. 161-173.
HENDERSON Ian, The Contemporary Law of Targeting: [Military Objectives, Proportionality and Precautions in Attack under Additional Protocol I], Leiden, Boston, M. Nijhoff, 2009, 266 pp.
HOLLAND Joseph, “Military Objective and Collateral Damage: their Relationship and Dynamics”, in YIHL, Vol. 7(2004), 2007, pp. 35-78.
MELZER Nils, Targeted Killing in International Law, Oxford, OUP, 2008, 468 pp. PARKER Tom, “The Proportionality Principle in the War on Terror”, in Hague Yearbook of International Law, Vol. 15, 2002, pp. 3-15.
PARKER Tom, “The Proportionality Principle in the War on Terror”, in Hague Yearbook of International Law, Vol. 15, 2002, pp. 3-15.
VALE MAJERUS Isabel, De quel droit ? Le droit international humanitaire et les dommages collatéraux, Paris, Le Serpent à Plumes, 2002, 229 pp.
WATKIN Kenneth, “Assessing Proportionality: Moral Complexity and Legal Rules”, in YIHL, Vol. 8(2005), 2007, pp. 3-53.
Further readings:
CANNIZZARO Enzo, “Contextualizing Proportionality: Jus ad Bellum and Jus in Bello in the Lebanese War”, in IRRC, Vol. 88, No. 864, December 2006, pp. 779-792.
COHEN Amichai, The Lebanon War and the Application of the Proportionality Principle, Jerusalem, Hebrew University of Jerusalem, May 2007, 26 pp.
COHEN Amichai, “The Principle of Proportionality in the Context of Operation Cast Lead: Institutional Perspectives, in Rutgers Law Record, Vol. 35, 2009, pp. 23-38.
DESGAGNÉ Richard, “The Prevention of Environmental Damage in Time of Armed Conflict: Proportionality and Precautionary Measures”, in YIHL, Vol. 3, 2000, pp. 109-129.
FENRICK William J., “The Law Applicable to Targeting and Proportionality after Operation Allied Force: A View from the Outside”, in YIHL, Vol. 3, 2000, pp. 5380.
FENRICK William J., “Targeting and Proportionality during the NATO Bombing Campaign against Yugoslavia”, in EJIL, Vol. 12/3, 2001, pp. 489-502.
KNOOPS Geert-Jan Alexander, “The Duality of the Proportionality Principle within Asymmetric Warfare and Ensuing Superior Criminal Responsibilities”, in International Criminal Law Review, Vol. 9, No. 3, 2009, pp. 501-529.
KRÜGER-SPRENGEL Friedhelm, “Le concept de proportionnalité dans le droit de la guerre. Rapport présenté au Comité pour la protection de la vie humaine dans les conflits armés, VIIIe Congrès de la Société internationale de droit pénal militaire et de droit de la guerre”, in RDMDG, Vol. 19, 1980, pp. 177-204.
MEDENICA Olivera, “Protocol I and Operation Allied Force: did NATO Abide by Principles of Proportionality?”, in Loyola of Los AngelesInternational and Comparative Law Review, Vol. 23, 2001, pp. 329-426.
NEUMAN Noam, “Applying the Rule of Proportionality: Force Protection and Cumulative Assessment in International Law and Morality”, in YIHL, Vol. 7 (2004), 2006, pp. 79-113.
PHILIPPE Xavier, “Brèves réflexions sur le principe de proportionnalité en droit humanitaire”, in En hommage à Francis Delpérée : itinéraires d’un constitutionnaliste, Mélanges No. 44, Brussels, Bruylant, 2007, pp. 1183-1196.
REYNOLDS Jefferson, “Collateral Damage on the 21st Century Battlefield: Enemy Exploitation of the Law of Armed Conflict and the Struggle for a Moral High Ground”, in Air Force Law Review, Vol. 56, 2005, 169 pp.
SHUE Henry & WIPPMAN David, “Limiting attacks on Dual Use Facilities performing Indispensable Civilian Functions” in Cornell International Law Journal, Vol. 35, 2002, pp. 559-579.
“Symposium: The International Legal Fallout from Kosovo” (articles of GAZZINI Tarcisio, HILPOLD Peter, CERONE John, FENRICK William J., BENVENUTI Paolo & BOTHE Michael), in EJIL, Vol. 12/3, 2001, pp. 391-536.
VENTURINI Gabriella, Necessità proporzionalità nell’uso della forza militare in diritto internazionale, Milano, Giuffrè, 1988, 189 pp.