Some Proportionality Issues Raised by Israel's Use of Armed Force in Lebanon

Frederic L. Kirgis
August 17, 2006


The current conflict between Israel and Hezbollah, which has resulted in extensive casualties and property losses in both Israel and Lebanon, raises important issues under the international law of armed conflict: the jus ad bellum (the right to resort to armed force, which generally turns on whether the U.N. Security Council has authorized the use of force or whether the force is properly used in self-defense) and the jus in bello (humanitarian law designed primarily to protect non-combatants and their property once an armed conflict has begun).

It is beyond the scope of a brief Insight to cover all of those issues.[1]  Instead, this Insight responds to questions that have been raised as to whether Israel's actions are proportionate to the actions and/or threat posed by Hezbollah.  Even within that limited focus, it does not attempt to deal with all of the points that could legitimately be raised regarding proportionality.  Instead, it seeks only to show (a) how one important international tribunal - the International Court of Justice (ICJ, or World Court) - has dealt with proportionality when it has been faced with that issue (primarily in the context of the law of self-defense within the jus ad bellum), and (b) how the body most directly concerned with the jus in bello - the International Committee of the Red Cross (ICRC) - has identified rules of customary international law that could apply to Israel's conduct of the war in Lebanon.  No attempt is made to reach conclusions regarding the legality of Israel's  (or Hezbollah's) actions. 

The ICJ and the Law of Proportionality

It is universally recognized that customary international law places two conditions on any use of force in self-defense:  the armed action taken must be necessary under the circumstances, and it must be proportional.[2]  This Insight does not address the necessity issue.  Moreover, as mentioned above, it addresses the proportionality issue only through the lens of ICJ decisions and opinions.  It should be noted, first of all, that ICJ decisions in contentious cases are binding only on the parties to the particular case, and ICJ advisory opinions are simply advisory, though they are influential.

The proportionality issue overlaps the distinction between jus ad bellum and jus in bello because it bears on how the conflict is conducted as well as on the permissibility of resorting to arms.  Thus, for example, a defensive military campaign might not be out of proportion to the attack defended against (a jus ad bellum issue), but some of the tactics used in the campaign might contravene the jus in bello if the risk to civilians or to civilian objects is disproportionate to the military advantage to be gained by using those tactics. 

"Proportionality" in the self-defense context could mean either that the intensity of force used in self-defense must be about the same as the intensity defended against, or it could mean that the force, even if it is more intensive than that, is permissible so long as it is not designed to do anything more than protect the territorial integrity or other vital interests of the defending party.  The two meanings are not necessarily mutually exclusive.  The former might be particularly applicable to skirmishes or relatively small-scale conflicts, while the latter might apply to particularly intense or large-scale conflicts.  The ICJ has had occasion to comment briefly on proportionality in the self-defense context.

In the case of Nicaragua v. United States, the ICJ addressed the international law issues surrounding U.S. support in the 1980s for the Nicaraguan "contras" against the Sandinista government of Nicaragua, but it did not clearly differentiate between the two possible meanings of "proportionality."  Referring to U. S. assistance to the Nicaraguan "contras" as a means of helping El Salvador defend itself against Nicaraguan-supported rebels in El Salvador, the Court said:

Whether or not the assistance to the contras might meet the criterion of proportionality, the Court cannot regard the United States activities . . . relating to the mining of Nicaraguan ports and attacks on ports, oil installations, etc., as satisfying that criterion.  Whatever uncertainty may exist as to the exact scale of the aid received by the Salvadorian opposition from Nicaragua, it is clear that these . . . United States activities  . . . could not have been proportionate to that aid.  Finally on this point, the Court must also observe that the reaction of the United States in the context of what it regarded as self-defence was continued long after the period in which any presumed armed attack by Nicaragua could reasonably be contemplated.[3]

The Case Concerning Oil Platforms (Iran v. United States) grew out of damage to a U.S. Navy frigate by a mine in the Persian Gulf during the Iran-Iraq war that raged during the 1980s.  In response to the mining, the United States launched Operation Praying Mantis, which included the shelling of two Iranian oil platforms apparently being used as radar stations, as well as the destruction of several Iranian naval vessels and aircraft.  The ICJ said that it "cannot close its eyes to the scale of the whole operation, which involved, inter alia, the destruction of two Iranian frigates and a number of other naval vessels and aircraft.  As a response to the mining, by an unidentified agency, of a single United States warship, which was severely damaged but not sunk, and without loss of life, neither 'Operation Praying Mantis' as a whole, nor even that part of it that destroyed the . . . platforms, can be regarded, in the circumstances of this case, as a proportionate use of force in self-defence."[4]

In a recent proceeding brought by the Democratic Republic of the Congo against Uganda, the ICJ dealt with Uganda's assertion that its use of armed force within the Congo was in self-defense.  The Court said in part that "the taking of airports and towns many hundreds of kilometres from Uganda's border would not seem proportionate to the series of transborder attacks it claimed had given rise to the right of self-defence ...."[5]

These ICJ pronouncements focus primarily on weighing the intensity of the defensive force against the intensity of the force defended against.  It is possible, though, that in a case where the stakes are higher, such as where the preservation of a state is at risk, the Court would take into account the overall defensive purpose in its assessment of proportionality.  In its Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons, the ICJ (after noting both the necessity and proportionality requirements for self-defense) said, "The proportionality principle may thus not in itself exclude the use of nuclear weapons in self-defence in all circumstances."[6]  The Court did not expressly condition that statement on first use of nuclear weapons by the opposing party.  It did, however, stress the applicability of principles of the humanitarian law of armed conflict that aim at the protection of civilians and civilian objects from unnecessary harm (the jus in bello).

Ultimately, by a seven-to-seven vote, representing the Court's opinion because of the Court President's casting vote, the Court said that although the use of nuclear weapons would generally be contrary to the rules of humanitarian law, "the Court cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defence, in which the very survival of a State would be at stake."[7]  Since nuclear weapons represent an extreme use of force, and since the Court did not limit itself to a scenario in which the attacking party uses nuclear weapons, the Court left open the possibility that - at least in a case involving self-preservation - its assessment of proportionality would not necessarily be confined to weighing the destructive intensity of defensive force against the intensity of the force defended against.

The ICRC and Protection of Civilians and Civilian Objects

The ICRC, the body that administers the 1949 Geneva Conventions and their 1977 Additional Protocols, has undertaken a study to determine which specific rules of customary international law may be drawn from state practice.[8]  According to the authors of the study, all of the rules quoted below are supported by state practice and can be regarded as customary international law applicable in both international and non-international armed conflicts.  They draw heavily, but not exclusively, on the Geneva Conventions and Protocols, particularly Protocol I.  But because they are set forth as rules of customary international law, they would apply even to states or entities that are not parties to any particular convention or protocol.  Thus, although there is a question whether the conflict between Israel and Hezbollah is technically "international" or "non-international" for purposes of the Geneva Conventions or Protocols (because it is a conflict between a state - Israel - and a nongovernmental group - Hezbollah - rather than between two states), the distinction does not matter if the same customary rules apply to either type of conflict.

The ICRC's study includes these arguably-relevant customary rules:

Rule 7. The parties to the conflict must at all times distinguish between civilian objects and military objectives.  Attacks may only be directed against military objectives.  *  *  *[9]

Rule 8. Insofar as objects are concerned, military objectives are limited to those objects which by their nature, location, purpose or use make an effective contribution to military action and whose partial or total destruction, capture or neutralisation, in the circumstances ruling at the time, offers a definite military advantage.

*   *   *

Rule 11. Indiscriminate attacks are prohibited.

Rule 12. Indiscriminate attacks are those [which] . . . are of a nature to strike military objectives and civilians or civilian objects without distinction.

Rule 13. Attacks by bombardment by any method or means which treats as a single military objective a number of clearly separated and distinct military objectives located in a city, town, village or other area containing a similar concentration of civilians or civilian objects are prohibited.

Rule 14. Launching an attack 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, is prohibited.


As has been stated above, this Insight does not take a position as to whether any particular actions in the conflict between Israel and Hezbollah are lawful or unlawful. It is intended, rather, to suggest a framework for analysis and to present some of the materials that might be relevant to a discussion of such questions.



About the author

Frederic L. Kirgis, an ASIL member, is Law School Association Alumni Professor Emeritus at the Washington and Lee University School of Law.  He has written books and articles on international law, and is an Honorary Editor of the American Journal of International Law.  The author is grateful to Richard Bilder and Michael Matheson for their comments on earlier drafts.  Any remaining errors, omissions or shortcomings are the author's own and not theirs.


[1] Some of the issues in the current conflict stem from the fact that Hezbollah is an armed group rather than a State.  Those issues will be covered in a separate Insight.  The present Insight's focus on  proportionality in light of Israel's use of force is not meant to suggest that there are no comparable issues raised by Hezbollah's use of force against Israel.

[2] See, for example, the International Court of Justice's Advisory Opinion on Legality of the Threat or Use of Nuclear Weapons, 1996 ICJ 226, 35 International Legal Materials 809 (1996), at paragraph 41.

[3] Military and Paramilitary Activities in and Against Nicaragua (Nicaragua v. United States), 1986 ICJ 14, 25 I.L.M. 1023 (1986), at paragraph 237.

[4] Case Concerning Oil Platforms (Iran v. United States), 2003 ICJ ___, 42 I.L.M. 1333 (2003), at paragraph 77.

[5] Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v. Uganda), 2005 ICJ ___, 45 I.L.M. 271 (2006), at paragraph 147.

[6] Advisory Opinion on Nuclear Weapons, note 2 supra, at paragraph 42.

[7] Id., paragraph 105, subparagraph 2.E.

[8] Jean-Marie Henckaerts & Louise Doswald-Beck, Customary International Humanitarian Law, Vol. 1: Rules (2005).  Although the study was carried out by these two members of the ICRC Legal Division (with some assistance from others), it carries the imprimatur of the ICRC itself.  The President of the ICRC has said, "The ICRC believes that the study does indeed present an accurate assessment of the current state of customary international humanitarian law."  Id. at p. xi.

[9] This rule does not deal with incidental damage resulting from attacks directed against military objectives.  Id. at p. 29.  But see Rule 14, above.