Proportionality is a fundamental component of the law on the use of force and the law of armed conflict—the jus ad bellum and the jus in bello. In the former, it refers to a belligerent’s response to a grievance and, in the latter, to the balance to be struck between the achievement of a military goal and the cost in terms of lives. The legitimate resort to force under the United Nations system is regarded by most commentators as restricted to the use of force in self-defense under Article 51 and collective security action under chapter VII of the UN Charter. The resort to force in both these situations is limited by the customary law requirement that it be proportionate to the unlawful aggression that gave rise to the right. In the law of armed conflict, the notion of proportionality is based on the fundamental principle that belligerents do not enjoy an unlimited choice of means to inflict damage on the enemy. Since the entry into force of Protocol I to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts, proportionality has been both a conventional and a customary principle of the law of armed conflict.
1 Documents on the Laws of War 5 n.2 (Adam Roberts & Richard Guelffeds., 2d ed. 1989); see also Myres M. McDougal & Florentino P. Feliciano, Law and Minimum World Public Order 241–44 (1961) (for their definition of proportionality in the jus ad bellum); and William V. O’Brien, The Conduct of Just and Limited War 27–31 (1981). James Turner Johnson, Just War Tradition and the Restraint of War 203 (1981), defines proportionality in the jus ad bellum sense as “where the total evil of the war is compared to its total good”; or “in contemporary language, the costs of the war must not outweigh the benefits,” id. at 204. In the jus in bello sense, proportionality has “to do with calculations of force necessary to subdue the enemy,” id. at 202.
2 The assertion by some commentators of the unilateral right to use force on the grounds of humanitarian intervention is the only exception to this consensus. See, e.g., Humanitarian Intervention (Richard B. Lillich ed., 1986); and Fernando R. Teson, Humanitarian Intervention (1988). Although the existence of the right to self-defense in international law is uncontroversial, what that right encompasses is the subject of endless debate. See, e.g., Derek W. Bowett, Self-Defence in International Law (1958); Ian Brownlie, International Law and the Use of Force by States 351–58 (1963); D. W. Greig, Self-Defence and the Security Council: What Does Article 51 Mean?, 40 Int’l & Comp. L.Q. 366 (1991); see generally Antonio Cassese, The Current Legal Regulation of the Use of Force (1986).
3 The locus classicus of the requirement of proportionality as an element of the customary law of self-defense is the Caroline incident. 7 John Bassett Moore, A Digest of International Law 919 (1906). The continuing role of proportionality in self-defense under the UN Charter was confirmed by the International Court of Justice in Military and Paramilitary Activities in and against Nicaragua (Nicar. v. U.S.), Merits, 1986 ICJ Rep. 14, 94, para. 176 (June 27). See also Brownlie, supra note 2, at 279 & esp. n.2; Ian Brownlie, Non-Use of Force in Contemporary International Law, in Non-Use of Force in International Law 17, 25 (William E. Butler ed., 1989); Oscar Schachter, International Law in Theory and Practice 153 (1991). It appears clear that proportionality is also a component of the exercise of force by way of collective security action under chapter VII of the Charter. For example, the then Secretary-General of the United Nations, Javier Pérez de Cuéllar, in the light of the conduct of the gulf conflict, referred to the need for reflection on the “mechanisms required for the [Security] Council to satisfy itself that the rule of proportionality in the employment of armed force is observed.” UN Dep’t of Public Information, Report of the Secretary-General on the Work of the Organization, UN Doc. DPI/1168-40923 (1991). See also Eugene V. Rostow, Until What? Enforcement Action or Collective Self-Defense?, 85 AJIL 506, 514 (1991).
4 Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of International Armed Conflicts, opened for signature Dec. 12, 1977, 1125 UNTS 3, reprinted in 16 ILM 1391 (1977) [hereinafter Protocol I]. See Articles 51(5)(b) and 57(2)(a)(iii), which encapsulate the concept of proportionality. The term “proportionality” does not appear in these provisions; rather, the word “excessive” is used in relation to civilian casualties. For more details on these articles, see text at notes 83–91 infra. The extent to which proportionality is a customary requirement and the extent to which the provisions of the Protocol represent the customary position on this point are controversial. See text at and note 92 infra.
5 Thomas M. Franck & Faiza Patel, UN Police Action in Lieu of War: “The Old Order Changeth,” 85 AJIL 63 (1991); Oscar Schachter, United Nations Law in the Gulf Conflict, 85 AJIL 452 (1991); Rostow, supra note 3; Burns H. Weston, Security Council Resolution 678 and Persian Gulf Decision Making: Precarious Legitimacy, 85 AJIL 516 (1991); Colin Warbrick, The Invasion of Kuwait by Iraq, 40 Int’l & Comp. L.Q. 482 (1991); and Thomas K. Plofchan, Article 51: Limits on Self-Defense, 13 Mich. J. Int’l L. 336 (1992).
6 Some writers would argue that this evaluation of the legitimate ends of the conflict is too narrow. See text at note 73 infra.
7 The effect of the failure to comply with proportionality in the jus ad bellum and the jus in bello is the same to the extent that in neither case can the actions be justified as lawful measures of self-defense. Moreover, breach of the requirements of proportionality in the conduct of hostilities is also a war crime. See Frits Kalshoven, State Responsibility for Warlike Acts of the Armed Forces, 40 Int’l & Comp. L.Q. 827 (1991).
8 Some work has been done on the requirements of proportionality in the law of armed conflict, particularly since the adoption of Protocol I. See, e.g., William J. Fenrick, The Rule of Proportionality and Protocol I in Conventional Warfare, Mil. L. Rev., Fall 1982, at 91; W. Hays Parks, Air War and the Law of War, 32 Air Force L. Rev. 1, 168–202 (1990); and John E. Parkerson, United States Compliance with Humanitarian Law Respecting Civilians During Operation Just Cause, Mil. L. Rev., Summer 1991, at 31. See also the two commentaries on the Protocols: Michael Bothe, Karl Josef Partsch & Waldemar A. Solf, New Rules for Victims of Armed Conflicts (1982); and Commentary on the Additional Protocols of 8 June 1977 to the Geneva Conventions of 12 August 1949 (Yves Sandoz, Christophe Swinarski & Bruno Zimmermann eds., 1987) [hereinafter Commentary]. As Brownlie writes, supra note 2, at 261–62, proportionality in the jus ad bellum has been largely neglected by international lawyers. For example, the sinking of the General Belgrano during the Falklands war, which raised questions about its legitimacy as an action in self-defense, was largely ignored by legal scholars, although regarded as extremely controversial in other quarters. The General Belgrano, at the time of the attack, was outside the “total exclusion zone” declared by the United Kingdom. The question was thus whether the sinking of a cruiser with over a thousand men on board was proportionate to the threat it posed. For details of this incident, see Max Hastings & Simon Jenkins, The Battle for the Falklands 147–50 (1983); and Richard Norton Taylor, The Ponting Affair (1985). The use of means of warfare such as chemical, biological and nuclear weapons also acutely raises questions of proportionality and has been addressed by scholars. See, e.g., Ann Van Wynen Thomas & A. J. Thomas, Jr., Legal Limits on the Use of Chemical and Biological Weapons 208–10 (1970); and Tom J. Farer, The Laws of War 25 Years After Nuremberg, Int’l Conciliation, May 1971. Just war scholars, on the other hand, have consistently focused on proportionality as a component of both the jus ad bellum and the jus in bello. See the sources cited in note 22 infra. However, the concept of proportionality in current international law and that contained in the just war theories of theologians and moral philosophers are significantly different. See, e.g., O’Brien, supra note 1.
9 But see Christopher Greenwood, The Relationship Between ius ad bellum and ius in bello, 9 Rev. Int’l Stud. 221 (1983). The declining interest in the relationship between these two branches of the law regulating the use of force is discussed further in text at note 32 infra.
10 Much of this debate concerns armed struggles involving the right of self-determination of peoples. Article 1(4) of Protocol I, supra note 4, treats wars of self-determination as international for the purposes of the application of the law of armed conflict. As a consequence, it is claimed that Protocol I, by introducing notions of the just war into humanitarian law, contains the seeds of destruction for the future protection of civilians in armed conflict. It is feared that this provision confers legality on these peoples’ resort to force and implicitly sanctions lower standards in achieving their goals. See, e.g., Letter of Transmittal (of Protocol II) from President Reagan, 81 AJIL 910 (1987); and Abraham D. Sofaer, The Rationale for the United States Decision, 82 AJIL 784 (1988). See also David E. Graham, The 1974 Diplomatic Conference on the Law of War: A Victory for Political Causes and a Return to the “Just War” Concept of the Eleventh Century, 32 Wash. & Lee L. Rev. 25 (1975); Guy B. Roberts, New Rules for Waging War: The Case against Ratification of Additional Protocol I, 26 Va. J. Int’l L. 107 (1985); Douglas J. Feith, Law in the Service of Terror—The Strange Case of Additional Protocol No. I, Nat’l Interest, Fall 1985, at 36; and Parks, supra note 8. Much of the initial controversy appears to have dissipated with the passage of time. As of December 31, 1992, 119 states had ratified or acceded to Protocol I and 109 states had ratified or acceded to Protocol II. 33 Int’l Rev. Red Cross 70–71 (1993). For the current attitude of states toward the Protocol, see George H. Aldrich, Prospects for United States Ratification of Additional Protocol I to the 1949 Geneva Conventions, 85 AJIL 1 (1991).
11 The Preamble to Protocol I reads in part;
Reaffirming further that the provisions of the Geneva Conventions of 12 August 1949 and of this Protocol must be fully applied in all circumstances to all persons who are protected by those instruments, without any adverse distinction based on the nature or origin of the armed conflict or on the causes espoused by or attributed to the Parties to the conflict.
12 For an analysis of the legal implications of the gulf campaign for the rules relating to noncombatant immunity, see Judith G. Gardam, Noncombatant Immunity and the Gulf Conflict, 32 Va. J. Int’l L. 813 (1992).
13 Disquiet has been expressed at the loss of civilian life as a result of the coalition forces’ bombing campaign in Iraq. See Schachter, supra note 5, at 465; and Weston, supra note 5, at 529. The full picture of the effects of the gulf conflict on civilians is only just emerging, and reliable information on the conduct of the conflict is difficult to obtain. There were several reports indicating that the so-called precision bombing of military targets by the coalition forces inflicted substantial civilian casualties. See, e.g., Brian Opeskin & Shelley Wright, War Crimes and the Gulf War, Current Aff. Bull. (Austl.), July 1991, at 12, 18. It appears, however, that the majority of the civilian casualties did not occur at the time of the attack, see Report to the Secretary-General on humanitarian needs in Kuwait and Iraq, UN Doc. S/22366 (1991), but resulted from the almost-complete destruction of the infrastructure of a highly developed state, with predictable impact on civilians. See Harvard Study Team, Public Health in Iraq After the Gulf War (1991); idem., Health and Welfare in Iraq After the Gulf Crisis (1991); Amnesty International, Report on the Gulf War (1991); Human Rights Watch, Needless Deaths in the Gulf War (1991); and Gulf War Casualties, New Internationalist, Oct. 30, 1991, at 30 (citing The Pacifist, No. 4, 1991).
14 Although it was envisaged that the Security Council would determine the aggressor in situations involving the use of force, until recently it had not performed this role. According to Greenwood, supra note 9, at 226, the practice of the Security Council has been to avoid designating one state as the aggressor.
16 See text at and note 33 infra.
16 The same fears were expressed about the inclusion under Protocol I of some conflicts involving the right of self-determination. See note 10 supra. It would be ironic if it turns out that this threat was always present in relation to traditional armed conflicts but unrealized because of the Security Council’s impotence.
17 For a description of just war theory, see Roger Bainton, Christian Attitudes Toward War and Peace (1960); James Turner Johnson, Ideology, Reason and the Limitation of War (1975); Frederick H. Russell, The Just War in the Middle Ages (1975); and Johnson, supra note 1.
18 On the law of arms based on the institution of chivalry, see Maurice H. Keen, The Law of Arms in the Middle Ages (1965).
19 See text at and notes 28, 31 infra.
20 On proportionality in the just war theory of St. Thomas Aquinas, see Paul Ramsey, War and the Christian Conscience 34–36 (1961); see also Johnson, supra note 1, at xxiii.
21 Johnson, supra note 1, at xxii; and James Turner Johnson, Can Modern War Be Just? 3 (1984).
22 Russell, supra note 17, at 307–08, after a comprehensive study of the just war theorists of the Middle Ages, concludes that during this period the justness of the resort to war legitimized the use of any means. Johnson, on the other hand, regards the jus in bello as a fundamental component of just war theory. See Johnson, supra note 1, for a comprehensive discussion of the development of the jus in bello over the centuries as a component of the just war and its various influences, canonical and secular. The interdependence in classical just war theory between the jus ad bellum and the jus in bello continues to be represented in modern just war theorizing but in a somewhat different form. The sharp delineation in the modern legal regime between the permissible resort to force and the conduct of hostilities, which developed during the period when resort to war was for the most part unregulated, never became part of the moral and philosophical just war analyses. The Christian focus, however, has tended in recent years to be as much concerned with the use of just means in modern warfare as with the justness of the resort to force, that is, it has concentrated on the jus in bello. See Ramsey, supra note 20; John K. Ryan, Modern War and Basic Ethics (1944); and John C. Ford, The Morality of Obliteration Bombing, 5 Theological Stud. 261 (1955). On proportionality in modern just war theory, see Paul Ramsey, The Just War 189–210 (1983); and Johnson, supra note 1, at 196–204. See generally Telford Taylor, Nuremberg and Vietnam: An American Tragedy (1970); Michael Walzer, Just and Unjust Wars (2d ed. 1991); and O’Brien, supra note 1.
23 St. Augustine is regarded as having first developed the Christian theory of the just war. There is no suggestion in St. Augustine’s theory of any significant limitations on the methods of warfare. See Russell, supra note 17, at 16–39; and Ramsey, supra note 20, at 14–33.
24 See Johnson, supra note 17, at 26–80. In Johnson’s view, the main foundation of the limits on warfare imposed by the jus in bello doctrine of the Middle Ages was the secular doctrine primarily derived from the chivalric code. See also text at and note 37 infra for a discussion of noncombatant immunity.
25 See Johnson, supra note 1, at 128; and Russell, supra note 17, at 156–57.
26 See text following note 34 infra.
27 See Johnson, supra note 1, at xxiii and 128–39, who queries whether this practice was dictated by considerations of proportionality since this limitation on weapons was restricted to wars between Christians. Johnson argues that the unnecessary suffering caused by the use of these weapons was not the issue. Rather, the ban on such weapons, more likely to be used by soldiers and mercenaries, was an attempt to limit warfare to the knightly classes.
28 In his treatment of the just causes of war, Grotius draws a distinction between moral and legal principles, derived respectively from Christian teachings and the law of nature. After defining the just and unjust causes of war, Grotius counsels against rash resort to war even in a just cause. A ruler should balance the evil and the good that may result from the just war. The effectiveness of the means to contribute to the good must be part of this balancing process and resort should be had to war only if the likely result will contribute more to good than to evil. This is a classic proportionality argument that Grotius illustrates by posing the dilemma between the forceful pursuit of freedom, which may result in the slaughter of one’s own people, and peace without freedom. The evil of the former, in his view, outweighs the good of the latter and thus does not warrant resort to war. Hugo Grotius, De jure belli ac pacis libri tres, bk. II, ch. XXIV, pts. V–VI (Carnegie ed., Francis W. Kelsey trans., 1925) (1646). See also Johnson, supra note 17, at 214.
29 Gerald Draper, The Development of International Humanitarian Law, in International Dimensions of Humanitarian Law 67 (1988); see also Geoffrey Best, The Place of Grotius in the Development of International Humanitarian Law, in Grotius rt l’ordre juridique international 101, 105 (Alfred Dufour, Peter Haggenmacher & Jifi Toman eds., 1985); and Benedict Kingsbury & Adam Roberts, Introduction: Grotian Thought in International Relations, in Hugo Grotius and International Relations 1, 20–21 (Hedley Bull, Benedict Kingsbury & Adam Roberts eds., 1990).
30 For example, in his discussion of “The Right of Killing Enemies in a Public War, and on Other Violence Against the Person,” Grotius’s first rule is that “[i]n war things which are necessary to attain the end in view are permissible.” Grotius, supra note 28, bk. III, ch. I, pt. II, at 599. Moreover, “this right of doing what is permissible has a wide application. … [I]t extends not only to those who actually bear arms, or are subjects of him that stirs up the war, but in addition to all persons who are in the enemy’s territory.” Id., ch. IV, pt. VI, at 646. This right, furthermore, extends to infants and women. Id., pt. IX, at 648. Frits Kalshoven, Grotius’ Jus in Bello with Special Reference to Ruses of War and Perfidy, in Grotius et l’ordre juridique international, supra note 29, at 89, 89–90, confirms that Grotius cannot be interpreted as suggesting any limitations on the conduct of warfare comparable to the requirements of the modern rule of proportionality. Nevertheless, for Grotius, what is permissible in a just war is not without moral limitations. For example, Chapter XI, Moderation with Respect to the Right of Killing in a Lawful War, contains the caution that “[n]ot even in a lawful war ought we to admit that which is said in the line, He, who refuses what is just, yields all.” Grotius, supra, bk. III, ch. XI, pt. I, at 722. On the issue of innocent persons, Grotius writes that “[i]t is the bidding of mercy, if not of justice, that, except for reasons that are weighty and will affect the safety of many, no action should be attempted whereby innocent persons may be threatened with destruction.” Id., pt. VIII, at 733–34. See also Draper, supra note 29, at 68.
31 Emmerich de Vattel, Droit des Gens (Carnegie ed., Charles G. Fenwick trans., 1916) (1758). Vattel further developed the idea discernible in the writings of Grotius that it was possible to have a war that was just on both sides. Id., bk. III, ch. III, §40, at 247. This led to greater emphasis in Vattel’s work on the jus in bello. Thus,
[a] part from the case in which there is no question of punishing an enemy, the whole may be summed up in this general rule; All acts of hostility which injure the enemy without necessity, or which do not tend to procure victory …, are unjustifiable, and as such condemned by the natural law.
Id., ch. IX, §172, at 294–95. See also Geoffrey Best, Humanity in Warfare 54–55 (1980).
32 See Lothar Kotzsch, The Concept of War in Contemporary History and International Law 83 n. 19 (1956); see also Christiane Shields Delessert, Release and Repatriation of Prisoners of War at the End of Active Hostilities 25 (1977).
33 See generally Draper, supra note 29; and Hugo Grotius and International Relations, supra note 29.
34 See Draper, supra note 29, at 67.
35 St. Petersburg Declaration Renouncing the Use, in Time of War, of Explosive Projectiles Under 400 grammes Weight, Dec. 11, 1868, 138 Consol. TS 297 (1868–69), reprinted in Documents on the Laws of War, supra note 1, at 30, 30–31. See further text at and note 41 infra; see also Commentary, supra note 8, at 477 (stating, in the context of the rule in Protocol I prohibiting the denial of quarter, that “[t]he deliberate and pointless extermination of the defending enemy constitutes disproportionate damage as compared with the concrete and direct advantage that the attacker has the right to achieve”).
36 See Alexander Pearce Higgins, Non-Combatants and the War 15 (1914), explaining, how ever, that civilians were at great risk during the bombardments of cities. See also Geoffrey Best, Restraints on War on Land Before 1945, in Restraints on War: Studies in the Limitation of Armed Conflicts 17, 27 (Michael Howard ed., 1979).
37 This norm requires parties to an armed conflict to distinguish at all times between civilians and combatants and between civilian and military objects and to direct their operations only against the latter. The norm is often referred to as the principle of distinction or discrimination and is variously denned. See, e.g., Frits Kalshoven, The Law of Warfare 27 (1973); John Bassett Moore, International Law and Some Current Illusions and Other Essays 5 (1924); Esbjorn Rosenblad, International Humanitarian Law of Armed Conflict: Some Aspects of the Principle of Distinction and Related Problems 53 (1979); and Richard R. Baxter, The Duties of Combatants and the Conduct of Hostilities, in International Dimensions of International Humanitarian Law 93, 103 (1988) (published posthumously).
38 During the era of the just war, canon law, through such means as the “Peace of God” and the “Truce of God,” developed categories of persons who were immune from the effects of warfare. Clerics, monks and friars, for example, were “entitled to full security against the ravages of war,” Johnson, supra note 1, at 127. As Johnson explains, the basis of this immunity was self-interest: to protect the institution of Christianity. Humanitarian considerations were not involved. Over the years, the categories of persons who were immune from warfare expanded in the interests of keeping the society stable. Once again, humanitarian considerations had no part to play. On the “Peace of God” and the “Truce of God,” see Frederick H. Russell, History of Medieval Christianity: Prophecy and Order 25 (1968); and Richard Shelly Hartigan, The Forgotten Victim: A History of the Civilian 65–77 (1982). According to Keen, supra note 18, at 190, these protections were totally ineffective in practice for the ordinary peasant. The secular chivalric tradition similarly provided protection for other groups. Johnson, supra, at 133–36.
39 This is not to suggest that such tolerance is inevitable. Support for the view that proportionality is an inappropriate concept in humanitarian law can be found in the travaux préparatories of Protocol I. See text at and note 84 infra. Cf. O’Brien, supra note 1, at 44 (describing the problems of reconciling the absolute immunity of noncombatants with the realities of modern warfare). Michael Walzer has reservations about the efficacy of proportionality as a means of making moral choices in relation to civilian casualties. Proportionality to him is limited to the requirement that no more civilians be killed than is militarily necessary; that is, no one can be killed for “trivial purposes.” In his view, civilians are entitled to more protection than this, if necessary involving the assumption of more risks by combatants. The law, he argues, provides no guidance on these difficult questions. See Walzer, supra note 22, at 151–56. However, the assumption of more risk by combatants can be built into the equation of proportionality. The fault lies not so much with the concept of proportionality as with the way it is interpreted. Moreover, it is arguable that the legal position and the rule of proportionality are not as Walzer states. Certainly, the provisions of Protocol I relating to indiscriminate attacks, discussed in detail in text following note 82 infra, demand a higher standard than the mere avoidance of intentional or trivial deaths and incorporate the very standard of due care that Walzer advocates for determining the legitimacy of civilian casualties. This aspect of the Protocol also appears to represent the customary law position. See text following note 92 infra.
40 This limitation was first codified in the Brussels Declaration (Article 12), a draft international agreement on the laws and customs of war, adopted by the Brussels Conference of 1874. The conference was summoned by Tsar Alexander II of Russia and attended by delegates of 15 European states. The Brussels Declaration, July 27, 1874, is reprinted in The Laws of Armed Conflicts 25 (Dietrich Schindler & Jiří Toman eds., 3d rev. ed. 1988). It was never ratified, as not all the parties were willing to accept it as a binding agreement.
41 Hague Convention Respecting the Laws and Customs of War on Land, Oct. 18, 1907, 36 Stat. 2277, 1 Bevans 631. Article 23 of the annexed Regulations reiterated the prohibitions contained in Article 13 of the unratified Brussels Declaration, supra note 40, and the Hague Convention of July 29, 1899, 32 Stat. 1803, 1 Bevans 247. Among the methods of warfare outlawed were the use of poison or poisoned weapons, the denial of quarter and the use of “arms, projectiles or material calculated to cause unnecessary suffering.” The general limitation of the Brussels Declaration on the means of injuring the enemy was also reiterated in Article 22 of the 1907 Regulations. The 1899 Hague Peace Conference also adopted two declarations on weapons: the Declaration 2 Concerning Asphyxiating Gases and the Declaration 3 Concerning Expanding Bullets, reprinted in Documents on the Laws of War, supra note 1, at 36, 40.
42 The other factor involved was humanity, a principle that was gaining in importance in the law of armed conflict. There is some dispute among commentators as to the role played by humanity in the rules on warfare, but it is beyond the scope of this study. See generally Thomas & Thomas, supra note 8, at 187–94.
43 The regulation of the means of warfare is nothing if not pragmatic. Morton William Royse, Aerial Bombardment and the International Regulation of Warfare 132 (1928), writes that “a weapon will be restricted in inverse proportion, more or less, to its effectiveness; … the more efficient a weapon or method of warfare the less likelihood there is of its being restricted in action by rules of war.” He provides the example of the explosive bullet outlawed by the St. Petersburg Declaration, supra note 35; after demonstrating its efficiency in aerial warfare, the bullet was excepted from this ban by Article 18 of the Hague Rules of Air Warfare, drafted Dec. 1922–Feb. 1923, reprinted in The Laws of Armed Conflicts, supra note 40, at 207.
44 Roberts and Guelff appear to regard this as a customary principle at the time of the St. Petersburg Declaration. Documents on the Laws of War, supra note 1, at 29–30.
45 For a description of aerial bombardment during the First World War, see Malcolm Cooper, The Birth of Independent Air Power (1986).
46 It was forbidden under Article 35 of the Hague Convention No. IV, supra note 41, to bombard undefended places, and commanders were under a duty to warn the inhabitants of defended places of the approaching bombardment. However, there was no obligation to allow the civilian population to leave before the bombardment commenced, although this practice was adopted by some commanders. See Higgins, supra note 36, at 14–15. For a discussion of the Hague Conventions and collateral damage to civilians, see Parks, supra note 8, at 17–20.
47 The term “indiscriminate” is used sometimes with different meanings. Usually, it refers to the targeting of military objects that results in disproportionate civilian casualties either through the choice of weaponry or through negligence in the conduct of the attack itself. Protocol I adopts this approach. See text following note 83 infra. Occasionally, “indiscriminate” may refer to the direct targeting of civilians. See, e.g., Parks, supra note 8, at 31; see also Hans Blix, Area Bombardment: Rules and Reasons, 49 Brit. Y.B. Int’l L. 31, 46 (1978).
48 See J. M. Spaight, Air Power and War Rights 225 (3d ed. 1947).
49 See, however, Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons which may be Deemed to be Excessively Injurious or to have Indiscriminate Effects, opened for signature Apr. 10, 1981, and annexed Protocol on Non-Detectable Fragments, Protocol on Prohibitions or Restrictions on the Use of Mines, Booby Traps and Other Devices, and Protocol on Prohibitions or Restrictions on the Use of Incendiary Weapons, UN Doc. A/CONF.95/15, Ann. I, at 20 (1980), reprinted in 19 ILM 1524 (1980).
50 According to Best, very little of the law of war prior to 1945 was concerned with the protection of civilians. Since then, however, its main focus has been on improving their protection. Best, supra note 36, at 27.
51 See Kalshoven, supra note 37, at 36; and Lassa Oppenheim, International Law 302 (Arnold D. McNair ed., 4th ed. 1926) (where the author refers to the inadequacy of the existing rules regulating air warfare).
52 See note 43 supra. In 1922–1923, an international conference of six states at The Hague established a Commission of Jurists to consider whether the existing rules were adequate to cover the emergence of new methods of warfare since the conclusion of the Hague Conventions and, if not, to consider what changes should be adopted. For a detailed discussion of the conference, see Moore, supra note 37, at 182. See also Lassa Oppenheim, International Law 518 (Hersch Lauterpacht ed., 7th ed. 1952). For the reasons states failed to ratify the Hague Rules, see Parks, supra note 8, at 35.
53 See generally Hamilton DeSaussure, The Laws of Air Warfare: Are There Any?, 5 Int’l Law. 527 (1971).
54 Hague Rules of Air Warfare, supra note 43, Art. XXIV. See also Oppenheim, supra note 52, at 522. For a detailed discussion of this whole topic, see the first edition of Spaight, supra note 48, at 212–38 (1924).
55 Oppenheim, supra note 52, at 524.
56 Spaight, supra note 54, at 225. See Parks, supra note 8, at 38–40, for an analysis of the provisions relevant to aerial bombardment in the military law manuals of the United States, the United Kingdom and Germany.
57 See, e.g., Charles G. Fenwick, International Law 550–51 (4th ed. 1965); and Lester Nurick, The Distinction Between Combatant and Noncombatant in the Law of War, 39 AJIL 680 (1945).
58 See Draper, supra note 29, at 179. It was estimated that aerial bombardment alone was responsible for the death of twelve million civilians and saturation bombing of civilian targets was widespread. See Howard S. Levie, When Battle Rages, How Can Law Protect? 70 (1971).
59 It appears that states initially were concerned to avoid the direct targeting of civilians and, moreover, to exercise care to avoid widespread civilian casualties. See Hersch Lauterpacht, The Problem of the Revision of the Law of War, 29 Brit. Y.B. Int’l L. 360, 365 (1952); and Parks, supra note 8, at 44–47. To a large extent, this was a stance taken for pragmatic reasons. It was militarily efficient to direct attacks against objects contributing to the enemy’s military capability. As the conflict developed, however, the perceived demands of military necessity eroded these standards. See David H. N. Johnson, Rights in Air Space 48 (1965), who writes that by 1941 the British Chiefs of Staff had included the morale of the enemy population as a target of aerial bombardment. The direct targeting of civilians so as to terrorize the population and thus bring an early end to the conflict was resorted to.
60 See, e.g., Lauterpacht, supra note 59, at 364–65. In Lauterpacht’s view, it was difficult to establish any further legal limitations on aerial bombardment to protect the civilian population. Johnson, supra note 59, at 57, after examining the instructions given to commanders in charge of aerial bombardment and the political rationale for these orders, took the same view. See also the summary of opinion in Blix, supra note 47, at 37–38. Some writers were prepared to go further. Spaight, supra note 48, at 277, was of the view that indiscriminate, as well as terror, bombardment remained unlawful. The practice of target area bombardment, however, in Spaight’s view was legitimate, which allows little content to his prohibition on indiscriminate attacks. See id. at 271–72.
61 In light of this prohibition, doubts were expressed about the desirability of further codifying the law of warfare, rather than concentrating solely on the prohibition of warfare. It was feared that such further attempts at codification involved some acknowledgment that conflict is inevitable and even acceptable. The International Law Commission in 1949 concluded that the law of war should not be considered for codification, as public opinion might interpret its action as showing lack of confidence in the means at the disposal of the United Nations for maintaining peace. Report of the International Law Commission to the General Assembly, 1949 Y.B. Int’l L. Comm’n 281. Cf. Roda Mushkat, Jus in bello revisited, 21 Comp. & Int’l L.J. S. Afr. 1, 10 (1988), who summarizes the arguments of writers who disagree that the jus in bello has become irrelevant in light of the Charter prohibition on the use of force.
62 See, e.g., Josef L. Kunz, The Chaotic Status of the Laws of War and the Urgent Necessity for Their Revision, 45 AJIL 37 (1951); Lauterpacht, supra note 59; Geza Herczegh, Development of International Humanitarian Law 84 (1984); and Best, supra note 31, at 316–17. The 1949 Convention protected only civilians in occupied territories, civilian medical establishments and interned civilians. Provisions guarding against making civilians the objects of attack were needed. The Hague Regulations, supra note 41, as we have seen, had merely provided that the right of belligerents to adopt means of injuring the enemy was not unlimited, and the customary principles were inadequate.
63 Protocol I, supra note 4; and Protocol Additional to the Geneva Conventions of 12 August 1949, and Relating to the Protection of Victims of Non-International Armed Conflicts, opened for signature Dec. 12, 1977, 1125 UNTS 606, reprinted in 16 ILM 1442 (1977) [Protocol II]. Protocol II contains no provisions relating to proportionality in the use of means and methods of warfare. See Judith Gail Gardam, Non-Combatant Immunity as a Norm of International Humanitarian Law 127 (1993). For a comprehensive analysis of the proceedings of the Diplomatic Conference and the provisions of Protocols I and II, see Bothe, Partsch & Solf, supra note 8; Commentary, supra note 8; and Howard S. Levie, Protection of War Victims: Protocol I to the 1949 Geneva Conventions (4 vols., 1979), which contains a compilation of documents regarding selected articles of Protocol I. On the work of the conference, see Richard R. Baxter, Humanitarian Law or Humanitarian Politics? The 1974 Diplomatic Conference on Humanitarian Law, 16 Harv. Int’l L.J. 1 (1975); David P. Forsythe, The 1974 Diplomatic Conference on Humanitarian Law: Some Observations, 69 AJIL 77 (1975); Charles L. Cantrell, Humanitarian Law in Armed Conflict: The Third Diplomatic Conference, 61 Marq. L. Rev. 253 (1977); and L. C. Green, The Geneva Humanitarian Law Conference 1975, 13 Can. Y.B. Int’l L. 295 (1975).
64 See Brownlie, supra note 2, at 41.
65 See R. Y. Jennings, The Caroline and McLeod Cases, 32 AJIL 82, 91 (1938); and Brownlie, supra note 2, at 43.
66 Brownlie, supra note 2, at 43.
68 Quoted in Jennings, supra note 65, at 89 (citing 29 Brit. & Foreign St. Papers 1129).
69 See, e.g., Brownlie, supra note 2, at 261; McDougal & Feliciano, supra note 1, at 241–44. The International Court of Justice in the Nicaragua case, 1986 ICJ Rep. at 94, 103, paras. 176, 194, confirmed that Article 51 of the Charter does not regulate specifically all aspects of the right to self-defense, in particular the requirements of proportionality and necessity; therefore, resort must be had to the preexisting customary rules.
70 See, e.g., Ved P. Nanda, The Validity of United States Intervention in Panama under International Law, 84 AJIL 494, 496 (1990). In Brownlie’s view, supra note 2, at 259, the difficulties of applying proportionality to anticipatory self-defense undermine arguments supporting the existence of such a right in international law.
71 The costs-benefits analysis of modern times, however, is much more complex and sophisticated than previously. For example, see the discussion of the assessment of proportionality in the political theory of limited war by Johnson, supra note 1, at 204–19.
72 As Brownlie writes, supra note 3, at 25, it is the most ignored aspect of self-defense. See, however, Schachter, supra note 3, at 153–54. The International Court of Justice considered proportionality in the Nicaragua case. The Court was of the view that actions such as attacks on ports and oil installations were not a proportionate response to the supply of aid to insurgents, irrespective of the level of that aid. 1986 ICJ Rep. at 122, para. 237. The issue was not, however, directly before the Court, as it found that the requirement of an armed attack had not been satisfied. Some commentators regard the U.S. action in Panama as infringing the requirements of proportionality. See Americas Watch, The Laws of War and the Conduct of the Panama Invasion 20 (1990). The legal justification for the use of force was itself debatable. See, e.g., Nanda, supra note 70; Tom J. Farer, Panama: Beyond the Charter Paradigm, 84 AJIL 503 (1990); Anthony D’Amato, The Invasion of Panama Was a Lawful Response to Tyranny, 84 AJIL 516 (1990); and Louis Henkin, Law and War After the Cold War, 5 Md. J. Int’l L. & Trade 147 (1991). The issue of proportionality, however, was whether a full-scale invasion lasting several weeks and resulting in the death of 26 Americans and several hundred Panamanians, mostly civilians, with widespread damage to property, was justified by incidents involving the physical harassment of a few U.S. citizens. Precise casualty figures, however, are difficult to obtain. See Parkerson, supra note 8, at 55 n.124.
73 It can be argued that this is too narrow an assessment of the legitimate aims of self-defense. For example, Rostow, supra note 3, at 514, argues that a component of legitimate self-defense is the protection of a party’s future security. He suggests, therefore, that in the gulf conflict the destruction of Iraq’s military capability would have been legitimate. This approach is predicated on the existence of the right to anticipatory self-defense, a highly controversial position. Even if this wider aim of self-defense in that conflict is accepted, the destruction of the infrastructure on which the civilian population depended is of marginal relevance to its achievement. Just war scholars would be critical of this analysis of the just aims of the conflict but for different reasons. For example, Robert Osgood & Robert Tucker, Force, Order and Justice 300–01 (1967), would regard such an approach, based as it is primarily on effectiveness, as very limited. As they explain, just war theory requires a more sophisticated balancing of the values to be gained against those that will be sacrificed.
74 See text following note 97 infra.
75 See Schachter, supra note 3, at 153. Cf. Walzer, supra note 22, at xv–xvii, who has more fundamental problems with proportionality, which he regards as a crude device and of limited value in drawing moral distinctions between just and unjust wars in contemporary times. For him, the mathe matical requirements of proportionality inevitably lead to pacifism, as it is only bodies that can actually be counted, not the values against which they are measured. This is, however, a narrow view of the potential of proportionality to determine the legitimacy of civilian casualties. In common with Osgood & Tucker, supra note 73, Walzer appears to base his criticism of proportionality on its failure, or for him its inability, to take into account a wider range of values. Perhaps it is true that the legal rule does not, and moreover cannot, perform this complex balancing process in a totally satisfactory way. Yet if it is acknowledged, as Walzer does, that aggression can and should be countered by the use of force in self-defense, then the narrower the aim against which the use of force is measured, the more effective proportionality will be as a means of limiting casualties. This approach is in fact at the heart of the Charter system and is one of the reasons for the efforts to retain the restricted interpretation of self-defense under its provisions.
76 The conventional and customary rules in this area are similar, although there are some important differences. Article 52(2) of Protocol I, supra note 4, defines military objectives and is declaratory of existing international law. See Remarks of Michael J. Matheson & Burrus M. Carnahan, in The Sixth Annual American Red Cross-Washington College of Law Conference on International Humanitarian Law: A Workshop on Customary International Law and the 1977 Protocols Additional to the 1949 Geneva Conventions, 2 Am. U. J. Int’l L. & Pol’y 415, 436 and 509, respectively (1987) [hereinafter Sixth Conference]. Paragraph 3, however, the presumption in cases of doubt about certain objects, appears to be an advance on the customary position. See Frits Kalshoven, Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts: The Diplomatic Conference, Geneva, 1974–1977, Part II, 9 Neth. Y.B. Int’l L. 107, 112 (1978).
77 See Schachter, supra note 3, at 154.
78 Walzer, supra note 22, at xx.
79 Such a change in the law would meet the concerns expressed by Walzer, id., that the attacks on targets supporting the Iraqi civilian population were “attacks on civilian society” and the military effects were collateral.
80 See, e.g., the sources cited in notes 84, 92 infra.
81 See also Bothe, Partsch & Solf, supra note 8, at 195.
82 See Protocol I, supra note 4, Arts. 48–58.
83 Indiscriminate attacks are:
(a) those which are not directed at a specific military objective;
(b) those which employ a method or means of combat which cannot be directed at a specific military objective; or
(c) those which employ a method or means of combat the effects of which cannot be limited as required by this Protocol;
and consequently, in each such case, are of a nature to strike military objectives and civilians or civilian objects without distinction.
Id., Art. 51(4).
84 Objections were expressed during the negotiation of this rule to the notion that any civilian casualties were acceptable. Several states, especially Romania, took this position. In particular, the subjective element inherent in the principle of proportionality was considered to be totally unacceptable. See Conf. Doc. CDDH/III/SR.31, para. 42, in 14 Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts, Official Records 305 (1978) [hereinafter Official Records].
85 The formula for determining whether the attack may be disproportionate is the same as that in paragraph 5(b) of Article 51, quoted in text following note 83 supra.
86 See Farer, supra note 8, at 16–17 (illustrating the different approaches to proportionality and the result that may ensue depending upon whether a military action is assessed alone or in relation to its contribution to an overall campaign). Thomas & Thomas, supra note 8, at 195–96, discuss this aspect of proportionality in relation to chemical and biological weapons. See also Bernard B. Brown, The Proportionality Principle in the Humanitarian Law of Warfare, 10 Cornell Int’l L.J. 134, 140 (1976); and Parks, supra note 8, at 173–74.
87 See Farer, supra note 8, at 16–17, whose graphic illustrations of the application of the principle of proportionality on a cumulative basis demonstrate the adverse consequences for civilians of this approach.
88 A grave breach of this provision, however, requires a subjective appreciation of the excessiveness of the attack. See Protocol I, supra note 4, Art. 85.
89 See Kalshoven, supra note 76, at 118.
90 On signing the Protocol, the United Kingdom made the following declaration in relation to Articles 51–58: “military commanders and others responsible for planning, deciding upon or executing attacks necessarily have to reach decisions on the basis of their assessment of the information from all sources which is available to them at the relevant time.” The text is reprinted in The Laws of Armed Conflicts, supra note 40, at 535. See also the statement by Canada in Conf. Doc. CDDH/SR.41, Annex, 6 Official Records, supra note 84, at 178.
91 Dual character targets are those such as power plants which serve both civilian and military purposes.
92 The scope of the Protocol is responsible for much of the controversy over the instrument. On the criticism regarding Article 1(4), see, e.g., note 10 supra. Other provisions of the Protocol, particularly those relating to the restrictions on the means and methods of warfare to improve civilian protection in armed conflict and thus the new provisions in relation to proportionality, have also been the subject of criticism. For example, the provisions on civilian protection were declared militarily unacceptable by the U.S. Joint Chiefs of Staff. See Sofaer, supra note 10. For further details of the U.S. military’s attitude in this regard, see Sixth Conference, supra note 76; and Customary Law and Additional Protocol I to the Geneva Conventions for Protection of War Victims: Future Directions in Light of the U.S. Decision Not to Ratify, 81 ASIL Proc. 26, 30 (1987).
93 Several of the states forming part of the coalition forces had ratified Protocol I. However, of the states actively involved in the conduct of the warfare—Iraq, France, Kuwait, Saudi Arabia, the United Kingdom and the United States—only Kuwait and Saudi Arabia had ratified or acceded to the Protocol. See 33 Int’l Rev. Red Cross, supra note 10.
94 Matheson, supra note 76, at 426 (then Deputy Legal Adviser, Department of State); see also Parkerson, supra note 8.
95 See U.S. Air Force, International Law—The Conduct of Armed Conflict and Air Operations, paras. 1-3a(2), 5-3c(1)(b) (1976).
96 U.S. Dep’t of the Army, The Law of Land Warfare (Field Manual 27-10,1956). Paragraph 41 states in relation to bombardment of defended places that “[l]oss of life and damage to property incidental to attacks must not be excessive in relation to the direct and concrete military advantage expected to be gained.” See paragraph 40 for the definition of “defended places.” Some commentators support the customary status of Article 51(5)(b). Bothe, Partsch & Solf, supra note 8, at 299, refer to paragraph 5(b) as a codification “in fairly concrete terms of the principle of proportionality as it applies to the protection of civilians against the collateral effects of attacks directed against military targets.” L. R. Penna, Customary International Law and Protocol I: An Analysis of Some Provisions, in Studies and Essays on International Humanitarian Law and Red Cross Principles 201, 220 (Christophe Swinarski ed., 1976), concludes that the provisions in Article 51 with respect to indiscriminate attacks and the principle of proportionality reflect customary international law. Antonio Cassese, The Geneva Protocols of 1977 on the Humanitarian Law of Armed Conflict and Customary International Law, 3 UCLA Pac. Basin L.J. 55, 88 (1984), considers the provisions on indiscriminate attacks to be customary, except as regards those states which explicitly reserve their right to self-defense and to differing interpretations of the rules on weapons. On the other hand, W. Hays Parks, Head of the International Law Team of the Office of the Judge Advocate-General of the Army, writes, supra note 8, at 173, that the U.S. military review of the Protocol concluded that its rule of proportionality was not customary in nature, although apparently the concept of proportionality is part of customary law. His view of the content of this latter concept is apparent from a document drawn up by Parks for discussion by senior military experts from Australia, Canada, Great Britain, New Zealand and the United States. According to this document, the concept of proportionality is designed to provide a “means for determining whether a nation or military commander responsible for planning, deciding upon, or executing a military operation has engaged in the intentional attack of civilians not engaged in the hostilities.” Quoted in id. at 174.
97 See Human Rights Watch, supra note 13, at 5–6. There are also reports that the imprecision of so-called smart bombs resulted in significant civilian casualties.
98 See the sources cited supra note 13. Article 54 of Protocol I is also relevant here, as it prohibits the targeting of objects indispensable to the survival of the civilian population. The definition of such objects is inclusive and refers to drinking water installations and supplies. The prohibition is inapplicable if, inter alia, the objects are used by the adverse party in direct support of military action. However, in the latter case, no action may be taken against these objects that may leave the civilian population to starve or force it to move away. Clearly, the actions of the coalition forces militate against considering the provisions of Article 54 as representing a customary law requirement.
99 See the sources cited in note 13 supra.
100 See Brown, supra note 86, at 143 (citing Thomas & Thomas, supra note 8, at 210).
101 See, e.g., the lengthy critique by one military expert of the provisions of Protocol I that place obligations on the attacker, as well as the party with control of the civilian population. Parks, supra note 8, at 149–68.
102 See, e.g., Matheson, supra note 75, at 422. Theodor Meron, Human Rights and Humanitarian Norms as Customary Law 74–76 (1989), is of the view that the practice of states whose interests are specially affected is a significant factor in the formation of custom from conventional norms. Cf. Michael Akehurst, Custom as a Source of International Law, 47 Brit. Y.B. Int’l L. 1, 22–23 (1974-75), who argues that the practice of some states is not inherently more important than that of others. It may, however, be more influential in reality by virtue of being more frequent and better publicized.
103 See the sources cited in Brownlie, supra note 2, at 406 n.1. This question also arose in the context of whether UN peacekeeping forces should be required to apply the entire law of armed conflict in their operations. In a report by the American Society of International Law’s Committee to Study Legal Problems of the United Nations, Should the Laws of War Apply to United Nations Enforcement Action’?, 46 ASIL Proc. 216, 220 (1952), the suggestion was made that the United Nations should be bound only by the laws of war that suited its purposes. The report attracted considerable criticism. See Mushkat, supra note 61, at 17; and Kotzsch, supra note 32, at 292–96.
104 Cf. SC Res. 660 (Aug. 2, 1990) (condemning the Iraqi invasion of Kuwait).
105 A final arbiter of the justness of the resort to force was intrinsic to the Christian doctrine of the just war. See, e.g., McDougal & Feliciano, supra note 1, at 133. With the decline in the overall authority of the church, how was the justness of the resort to force to be determined? As one writer explains, it had to be left to each state; war could thus be subjectively just on both sides, which logically could lead to the legality of every resort to force. Josef L. Kunz, Bellum Justum and Bellum Legale, 45 AJIL 528, 531 (1951).
106 See further McDougal & Feliciano, supra note 1, at 530–34. Similarly, the individual is separated from the state in the context of responsibility for breaches of the law of armed conflict. See 22 Trial of the Major War Criminals Before the International Military Tribunal 456–66 (1948).
107 See Theodor Meron, Human Rights in Internal Strife: Their International Protection (1987); and Meron, supra note 102.
108 United States v. List, 11 Trials of War Criminals Before the Nuernberg Military Tribunals Under Control Council Law No. 10, at 1230, 1247 (1948) (quoting Oppenheim as author of British Manual of Military Law 79).
109 See Schachter, supra note 5, at 466.
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