Elements of an Act of Aggression: An Overview of Modern International Law and Practice

Abstract

The Charter of the United Nations is the principal source of contemporary international law for the regulation of the use of force in inter-State relations. It sets out the interrelated competences of the main bodies of the United Nations—first of all, of the Security Council, the General Assembly and the International Court of Justice—in the area of maintaining international peace and security, and confirms States’ inherent right of self-defence as a matter of applicable customary international law. The Charter’s main provision pertaining to the prohibition of the use of force—Article 2(4)—is at the heart of the in-depth legal analysis, as a rule of conventional and customary international law as well as one of jus cogens. The chapter suggests that any use of force not falling within one of three categories—Charter-based exceptions, Charter-related exceptions and extra-Charter exceptions to the prohibition of the use of force—might potentially qualify as aggression and entail consequences provided for under international law, including the individual criminal responsibility of its authors.

As was discussed above (see supra 1.2.5), a major objective of the modern international legal order, which is founded upon the Charter of the United Nations, consists in the maintenance of international peace and security. Contrary to a widespread opinion, the Charter contains more than just a few articles relating to the use of armed force¹—there are, in effect, many more, from which circumstance it must be inferred that the conditions under which force can be used under current international law are more strictly defined than some scholars have suggested.² Article 2(4) of the Charter laid down a fundamental restriction on the use of force in international relations (see infra 2.1.1)—an obligation which was, from its inception, designed to be of a superior legal nature³ and is now recognized to have acquired the character of customary international law (see infra 2.1.2) and even that of jus cogens (see infra 2.1.3). Notably, Peter Malanczuk suggests that this norm is now binding even for the few States which are not Members of the United Nations.⁴

Permitted uses of force are regulated by a sequence of the Charter’s provisions, which is opened with the seventh preambular paragraph: “[T]o ensure […] that armed force shall not be used, save in the common interest […]” (emphasis added). Although the Preamble does not per se possess a legally binding force,⁵ it does provide an indication as to the spirit of the subsequent articles. In line with the Preamble’s “common interest” clause, Article 1(1) lists among the purposes of the United Nations “effective collective measures for the prevention and removal of threats to peace, and for the suppression of acts of aggression or other breaches of peace” (emphasis added, see infra 2.4.1.5).⁶ At least, two of the United Nations main organs, the General Assembly (Article 12, cf. supra 1.2.5.3 and infra 2.4.2.1) and the Security Council (Articles 24(1) and 39, cf. supra 1.2.5.2 and infra 2.4.1.5), were given powers to react, albeit in different manners, to threats to peace, breaches of peace, and acts of aggression.⁷ Chapters VII (“Action with Respect to Threats to the Peace, Breaches of the Peace, and Acts of Aggression”) and VIII (“Regional Arrangements”) are devoted in their entirety, correspondingly, to the maintenance of international peace and security through collective action under the auspices of the United Nations or of regional arrangements. More specifically, Article 42 endows the Security Council with the authority to “take such action by air, sea or land forces as may be necessary to maintain or restore international peace and security.” Article 43 was intended to set a framework for the conclusion of agreements between the Security Council and the United Nations Member States who would participate in the maintenance of international peace and security, and Article 44 is devoted to specific relations between the Security Council and Member States who, not being members of the Security Council, would participate in such operations (for a discussion, see infra 2.4.1.5.2). The fundamental Article 51 recognizes the Member States’ “inherent right to self-defence” against armed attacks (see infra 2.4.1.1–2.4.1.4). Finally, already outdated Articles 53 and 107 of the Charter address the use of force, where necessary, against former enemies in the Second World War. ⁸

During the period since the 1999 NATO operation in Kosovo,⁹ and especially in connection with the US-led Operation Enduring Freedom (Afghanistan)¹⁰ and, subsequently, Operation Iraqi Freedom (Iraq), a number of novel doctrines have been put forward with a view to justifying these uses of force (cf. supra 1.1.2.3)—potentially an important development in a field of international law as conservative as the post-1945 jus ad bellum,¹¹ for, at times, these doctrines claimed to be as far-reaching as to be able to modify the Charter’s provisions on the use of force. By contrast, it is argued in this chapter that Article 2(4) and relevant customary international law should not be interpreted in too broad a manner,¹² and that any use of force in inter-State relations, which would not be compatible with the overarching prohibition contained in Article 2(4), would accordingly constitute a breach of the Charter.¹³ Then again, since not all unlawful uses of inter-State armed force constitute acts of aggression (see infra 2.3 and 5.1.1.2–5.1.1.3),¹⁴ and hence entail individual criminal liability under customary international law (see infra 4.1–4.2) and the Rome Statute of the International Criminal Court (see infra Chap. 5), it will be an aim of this chapter to distinguish between distinctively aggressive and other, less grave, unlawful uses of inter-State armed force which, though breaching Article 2(4), would not (necessarily) entail individual criminal responsibility.

1 Nature of States’ Obligation to Refrain from the Threat or Use of Force in International Relations (Article 2(4) of the UN Charter)

As the Covenant of the League of Nations (see supra 1.1.6.2) and the Kellogg-Briand Pact (see supra 1.1.6.5) were unable to prevent the Second World War, it was an aim of the drafters of the Charter of the United Nations to remedy the deficiencies of both instruments (see supra 1.2.5).¹⁵ The ambitious reform which they undertook to accomplish was without a precedent in that it sought to transform the traditional jus ad bellum, which had not excluded States’ right to use force in furtherance of their foreign policies, into a novel jus contra bellum, which not only outlawed war as a legitimate means of settlement of international disputes but also banned most uses of military force short of war and even threats to use force in international relations.¹⁶ This section examines the relevant rule contained in the Charter as a conventional one (see infra 2.1.1), as one of customary international law (see infra 2.1.2) and of jus cogens (see infra 2.1.3).

1.1 Treaty Obligation Under Article 2(4)

A provision of paramount importance, Article 2(4) has been referred to as “the cornerstone of peace in the Charter,” “the heart of the United Nations Charter” or the “basic rule of contemporary public international law.”¹⁷ Undoubtedly, Article 2(4) is by far better worded than was Article 1 of the Kellogg-Briand Pact (cf. supra 1.1.6.5), for it prohibits the use of force in general and not only war, and covers even threats of force. Besides, this rule of international law, in conjunction with related ones (see supra introductory note to this chapter), creates—in the words of Albrecht Randelzhofer, at least in theory—an institutional United Nations system of collective sanctions against any offender (Articles 39–51).¹⁸ However, as will be seen, even this major provision is not without ambiguities. As adopted at the San Francisco Conference, Article 2(4) reads:

All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.

1.1.1 Protected States and Values

The content of Article 2(4) raises a number of legal and technical issues. First, whilst formally creating legal obligations only for the United Nations Members, the provision in fact protects Members and non-Members (“any State”) alike.¹⁹ Second, it singles out two groups of objects which are protected against unlawful threats or use of force under the Charter: on the one hand, States’ territorial integrity and political independence are mentioned as specific examples of protected values; on the other hand, it is also forbidden to issue threats or use force “in any other manner inconsistent with the Purposes of the United Nations.” These two groups of protected values, although equated in one provision, are not quite of the same nature (because Article 2 technically lists the institutional Principles—not the Purposes—of the United Nations). Whereas the territorial integrity and political independence are referred to in Article 2(4) expressly and in a self-contained manner, the purposes of the United Nations are listed separately in Article 1 of the Charter and include:

• the maintenance of “international peace and security” and related undertakings to that end (Article 1(1));

• developing “friendly relations among nations based on respect for the principle of equal rights and self-determination of peoples,” and taking “other appropriate measures to strengthen universal peace” (Article 1(2));

• developing “international co-operation in solving international problems of an economic, social, cultural, or humanitarian character, and in promoting and encouraging respect for human rights and for fundamental freedoms for all without distinction as to race, sex, language, or religion” (Article 1(3));

• and being “a centre for harmonizing the actions of nations in the attainment of these common ends” (Article 1(4)).

Nonetheless, since both parts of the phrase are to be read in conjunction, one may conclude that the purposes of the United Nations are, as objects protected under Article 2(4) of the Charter, of an equal value with the territorial integrity and political independence of States. Importantly, an inverse interpretation of Article 2(4) appears to suggest that (Members of) the United Nations might lawfully threaten to use force in their international relations, or use it, in order to preserve the territorial integrity or political independence of theirs or, in appropriate circumstances, also of (an)other State(s), or in another manner, which would be consistent with the Purposes of the United Nations. The foremost exceptions to the prohibition contained in Article 2(4) will be considered below at 2.4.

1.1.2 The Meaning of “Force”

The meaning of the notion “force” referred to in Article 2(4) is essential. It is generally agreed among scholars that this provision covers, in the first place, the threat or use of armed or military force—i.e., the employment by a State of its regular armed forces²⁰ (in a broad sense currently accepted in international law²¹), or of irregular armed groups.²² and of means²³ and methods of warfare (in the sense of applicable international humanitarian law) against another State, its nationals, public or private property. Although Article 2(4) contains no qualification of the term “force,” one may derive this conclusion from the Charter’s related provisions (for example, from Articles 41 and 46 where this explicit qualification is found), the 1970 Friendly Relations Declarations and from the Charter’s travaux préparatoires: it is known, for instance, that the proposal Brazil made on 6 May 1945 at the San Francisco Conference with a view to extending the prohibition of force to economic coercion, was explicitly—and quite correctly—rejected.²⁴ As Albert Randelzhofer notes, an extension of Article 2(4) to other forms of force would result in leaving States virtually with no internationally lawful means of exerting pressure upon States that violate international law.²⁵ Correspondingly, the first Principle in the 1970 Declaration on Principles of International Law Concerning Friendly Relations and Cooperation among States in Accordance with the Charter of the United Nations, which interpreted Article 2(4), dealt solely with the military force,²⁶ and the prohibition of economic, political and other types of coercion was covered under the heading of non-intervention.²⁷

The following sections will briefly examine the use of two particular types of force—the so-called “physical” and “indirect” force—which, while being distinct from the use of armed force, may, in some circumstances, entail the effects of the latter (first and foremost, the exercise by a State of its right to self-defence (cf. infra 2.4.1.1–2.4.1.4).

1.1.2.1 Physical (Non-military) Force

It is submitted that in situations where a State does not resort to its armed forces, irregulars or means and methods of warfare (cf. supra 2.1.1.2) against another State, its nationals, public or private property, there is no use of military force in the sense of Article 2(4) of the UN Charter. Even so, States can be affected by forcible measures of a social, natural or technical kind not involving the use of military force in a proper sense of the word—i.e. by manifestations of the so-called “physical” force—whose effects at times can be just as critical as those of military force.²⁸ It appears that a contemporary—and most relevant—example of physical non-military force, which, as a matter of fact, did produce the effects of an armed attack, were the terrorist attacks of 11 September 2001 in New York, Washington, D.C. and Pennsylvania.²⁹ They were of such an unparalleled magnitude that the UN Security Council pronounced in its resolution 1368 (2001)³⁰ that “such acts, like any act of international terrorism, [were] a threat to international peace and security” (emphasis added), and emphasized “that those responsible for aiding, supporting or harboring the perpetrators, organizers and sponsors of these acts [should] be held accountable.”³¹ These provisions necessitate at least two observations for the purpose of our argument. First, the Security Council held “any act of international terrorism”—including the specific ones, which occurred on 11 September 2001—to be a threat to international peace and security considerable enough to be commensurate with the invocation by a victim State of its “inherent right of individual or collective self-defence in accordance with the Charter,”³² i.e., one comparable to an “armed attack” in the sense of Article 51 of the Charter (cf. infra 2.4.1.1). Yet, in this author’s view, the attacks of 11 September 2001 were, stricto sensu, not “armed,” unless the hijacked civilian airplanes were to be regarded, by analogy, as “military weapons.” True, the airplanes have been used to perform the destruction they did but they were not meant, by their primary function, to be used for killing people and destroying property, and should therefore not be regarded as “military weapons” or “means of warfare” in the sense of applicable international law. The Security Council’s reference to Article 51 was entirely appropriate in the light of the 9/11 terrorist attack’s effects comparable to those of an armed attack but not because of the attack’s armed or military nature.

Second, the attack of 11 September 2001 was carried out not by a State, or on behalf of a State, but by a non-State actor on its own behalf. That an act of aggression can, in accordance with current theory, only be committed by a State (see infra 3.1.5), might be yet another reason for not having termed the attack an act of aggression. As a matter of fact, Article 51 of the UN Charter does not specify that an armed attack in respect of which a State’s right of individual or collective self-defence may be invoked must of necessity be committed by a State. It states that “[n]othing in the present Charter shall impair the inherent right of individual or collective self-defence, if an armed attack occurs against a Member of the United Nations” (emphasis added), without specifying the origin of the armed attack. Accordingly, a literal interpretation of Article 51 suggests that every Member of the United Nations has an inherent right to individual or collective self-defence against any kind of armed attack, be it carried out by another State or a non-State entity. The decisive issue is therefore that of accommodating Article 51’s requirement that the attack in question be armed, whereas the attack of 11 September 2001 was, as was discussed above, of an extremely violent but still non-military nature; it was the effect of the attack that placed it on an equal footing with an armed one. To conclude, the United States, befallen by an international terrorist attack, was right in invoking Article 51 but that invocation should have been founded on the quasi-military effects of the physical attack rather than on its ostensibly military nature. More generally, a State finding itself under an international terrorist attack is certainly entitled to repel it, including by military means, individually or collectively, without thereby violating Article 2(4) of the Charter, but the precise justification of an invocation of the right to self-defence under Article 51 should depend on the circumstances in each case.

1.1.2.2 “Indirect Force”

As was discussed above at 2.1.1.2, the scope of Article 2(4) is indeed limited to the proscription of armed force but, notably, this proscription also embraces the concept of “indirect force.” This notion generally stands for a State’s technical or organizational involvement in an international armed conflict ongoing between other States (cf. infra 5.1.1.3.6), or else in a non-international armed conflict occurring in another State³³—for example, by sending to that State armed bands, groups, irregulars or mercenaries (cf. infra 5.1.1.3.7). The UN General Assembly interpreted the prohibition of indirect force in the 1970 Friendly Relations Declaration (cf. supra 1.2.5.3) as follows:

Every State has the duty to refrain from organising or encouraging the organization of irregular forces or armed bands, including mercenaries, for incursion into the territory of another State.

Every State has the duty to refrain from organizing, instigating, assisting or participating in arts of civil strife or terrorist acts in another State or acquiescing in organized activities within its territory directed towards the commission of such acts, when the acts referred to in the present paragraph involve a threat or use of force.³⁴

Obviously, as Albrecht Randelzhofer notes, both prohibited modes of action—the organization or encouragement of irregular forces or armed bands, on the one hand, and the prohibition of participation in acts of civil strife or terrorist acts, on the other hand—are worded in such a broad manner that virtually every act of technical or organizational support rendered by a State would be covered by “organizing,” “encouraging,” “instigating,” “assisting” or “participating,” and the meaning of “armed force” under international law would thereby almost inevitably be blurred.³⁵ With a view to avoiding this effect, the International Court of Justice made a proper observation in the Nicaragua Judgment that not every act of assistance should be regarded as a use of force.³⁶ However, the Court did not suggest any definitive criteria for determining which acts of assistance, and in which circumstances were to be viewed as an internationally wrongful threat or use of force in the sense of Article 2(4) of the Charter.³⁷ It appears that such a criterion might consist in the legal evaluation of the threat or use of force itself, and the employment of “indirect force” in its furtherance would derive its (il)legality from that of the main effort. In other words, providing assistance in the circumstances of an internationally lawful use of force should be regarded as lawful, whereas employing “indirect force” in support of a threat or use of force in breach of Article 2(4) of the Charter would itself constitute a breach thereof. Should the International Law Commission be tasked with producing the “Draft Articles” on the use of force by States (see supra 1.2.5.3), its expert opinion on the issue of “indirect force” might hopefully contribute to resolving the normative ambiguity left unanswered by the International Court of Justice in the Nicaragua Judgment.

1.2 Obligation Under Customary International Law

In addition to its conventional nature (see supra 2.1.1), some publicists deem Article 2(4) of the Charter to also be part of customary international law.³⁸ Yet, this point of view is only partially accurate. In the Nicaragua Judgment, the International Court of Justice held that the use of force was also—in addition to its being subject to the Charter’s conventional provisions—regulated by customary rules of international law, the content of which was not necessarily identical to that of the treaty provisions:

As regards the suggestion that the areas covered by the two sources of law are identical, the Court observes that the United Nations Charter […] by no means covers the whole area of the regulation of the use of force in international relations.³⁹

The ICJ held explicitly that the operation of the Charter did not either “subsume” or “supervene” applicable customary international law,⁴⁰ and that “the areas governed by the two sources of law [did] not exactly overlap, and the substantive rules in which they are framed [were] not identical in content.”⁴¹ Moreover, the Court ruled that nothing should impair the parallel applicability of a relevant customary norm, even if a conventional norm and a customary norm were to have exactly the same content.⁴² This leads us to a discussion of the International Court of Justice’s view of customary international law on the prohibition of the use of force between States, as it was reflected in the Nicaragua Judgment, with a view to reconciling it with Article 2(4).

1.2.1 Article 2(4) of the UN Charter Versus Customary International Law

This distinguished Judgment has, in fact, been somewhat inconsistent on a few essential points. Having, on the one hand, acknowledged the primacy of the Charter of the United Nations in the legal regulation of the use of force in international relations, the ICJ nonetheless considered it apposite to “supplant” the Charter’s relevant rules by customary international law applicable to a given case.⁴³ Having further claimed to embark on the determination of such rules, the Court, in fact, limited itself to concluding that the practice of States must “in general, be consistent” with the rules in question,⁴⁴ without considering the idiosyncratic particulars of such practice in a more comprehensive fashion. And, finally, when assessing the opinio juris on the subject, the ICJ regarded, quite inaccurately, a few non-binding (“soft law”) sources as constituting evidence of States’ opinio juris on the prohibition of the use of force.⁴⁵

As was noted above at 2.1.2, the Court’s starting point was that the legal regulation of the use of force in international relations was not limited to the United Nations Charter and also included rules of customary international law.⁴⁶ The Court referred, by way of providing an example of continued application of customary international law alongside the Charter, to its Article 51—a State’s inherent right to individual or collective self-defence.⁴⁷ Having restated the Charter text that “nothing [in the present Charter] shall impair” the realization of this inherent right in the event of an armed attack, the Court concluded that Article 51 would only be meaningful on the assumption that the right in question were of a customary nature—even if its present content was indeed confirmed and influenced by the Charter⁴⁸ (for a detailed discussion of States’ right to self-defence, see infra 2.4.1.1–2.4.1.4). Nor did the Charter regulate all aspects of the right’s content and ways of implementation: for example, it did not contain any rule to the effect that individual or collective self-defence would warrant only measures which are proportionate to the armed attack and necessary to respond to it efficiently—a rule well established in customary international law.⁴⁹ The ICJ observed likewise that the notion of “armed attack,” which triggers the exercise of the right of self-defence by the State(s) affected by the attack, was not defined in the Charter, and was not part of either general or particular treaty law either.⁵⁰ In the absence of detailed conventional regulations on such issues, the Court could not plausibly conclude that Article 51 of the UN Charter “subsume[d] and supervene[d]” applicable customary international law. Instead, the ICJ concluded that, with regard to the use of force in inter-State relations, customary law continued to apply alongside treaty law, and that the areas governed by the two sources of international law did not “overlap exactly.”⁵¹

1.2.2 Customary International Law on the Use of Force: The State Practice

Substantial problems started emerging when the Court attempted to identify the gist of rules of customary international law governing the use of force in inter-State relations. Having noted that there existed a substantial degree of accord between Nicaragua and the United State as to the applicable rules of customary law,⁵² the Court nevertheless declared its willingness to deal with the matter:

This concurrence of their [the Parties’] views does not however dispense the Court from having itself to ascertain what rules of customary international law are applicable. The mere fact that States declare their recognition of certain rules is not sufficient for the Court to consider these as being part of customary international law, and as applicable as such to those States. Bound as it is by Article 38 of its Statute to apply, inter alia, international custom “as evidence of a general practice accepted as law”, the Court may not disregard the essential role played by general practice. Where two States agree to incorporate a particular rule in a treaty, their agreement suffices to make that rule a legal one, binding upon them; but in the field of customary international law, the shared view of the Parties as to the content of what they regard as the rule is not enough. The Court must satisfy itself that the existence of the rule in the opinio juris of States is confirmed by practice.⁵³

The Court did not thereby require “that in the practice of States the application of the rules in question should have been perfect, in the sense that States should have refrained, with complete consistency, from the use of force or from intervention in each other’s interna1 affairs.”⁵⁴ In other words, the Court was not of the view that, in order for Article 2(4) and other relevant rules of the UN Charter to be recognized as customary, the corresponding State practice must be in exact conformity with those rules. Instead, the ICJ deemed it sufficient that the State practice⁵⁵ be in general consistency with such rules, and that instances of State conduct inconsistent with a given rule should generally be treated as breaches of that rule, and not as indications of the recognition of a new rule:

If a State acts in a way prima facie incompatible with a recognised rule, but defends its conduct by appealing to exceptions or justifications contained within the rule itself, then whether or not the State’s conduct is in fact justifiable on that basis, the significance of that attitude is to confirm rather than to weaken the rule.⁵⁶

In the opinion of Nicholas Tsagourias, the ICJ allowed for a methodological inaccuracy in that it focused predominantly on the opinio juris, from which it deduced, almost mechanically, the conformity of State practice and refused to test the actual practice of States with respect to the prohibition of the use of inter-State force.⁵⁷ It appears that the issue of State practice in an area as crucial and delicate as this should have been treated with more attention, for at present it is not sufficiently measurable. Michael J. Glennon observes that, according to the 2004 Report of the High-Level Panel on Threats, Challenges and Change,⁵⁸ “from 1945 to 1989, states used military force numerous times in interstate disputes. By one count, force was employed 200 times, and by another count, 680 times.”⁵⁹ In other words, he goes on, “the panel does not tell us who is right; indeed, it does not seem to care who is right. Apparently, it would not matter whether the rules had been violated 200 or 680 or 6800 times—the panel seems to suppose the number of violations is irrelevant.”⁶⁰ However, he continues, the actual number of violations of a rule is important, for at least two reasons:

First […] the report rejects humanitarian intervention by states. The reason, the report says, is that humanitarian intervention by states would pose a fatal risk to the stability of the global order. Yet, how can we know how great the threat would be to the stability of the global order unless we know how stable that order really is—unless we know how effective the current rules actually have been in preventing the use of force?

Second, after the number of violations exceeds a certain point, it is reasonable to conclude that states no longer consent to the rule and that the rule is no longer binding—that it has fallen into desuetude. Without examining the extent of non-compliance, however, it is impossible to know whether the rule is still a good law. Why does the panel assume that the law is what it believes the law should be?⁶¹

1.2.3 Customary International Law on the Use of Force: The opinio juris

As concerns the opinio juris, the Court did not produce any more clarity on the matter either, for it followed from the Parties’ submissions to the Court that they regarded Article 2(4) as being generally reflective of customary international law on the issue in question, and that they did not challenge the obligation emanating from that Article “to refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any State, or in any other manner inconsistent with the purposes of the United Nations.”⁶² The Court nonetheless felt that it had to go beyond the submissions of the States involved in the dispute, and to satisfy itself as to the existence in customary international law of a more universal opinio juris of the mandatory character of this rule. According to the Court, an adequate opinio juris might be inferred from, inter alia, the attitude of the parties to the dispute and of other Members of the United Nations towards relevant General Assembly resolutions, especially towards the 1970 Friendly Relations Declaration (see supra 1.2.5.3):

The effect of consent to the text of such resolutions cannot be understood as merely that of a “reiteration or elucidation” of the treaty commitment undertaken in the Charter. On the contrary, it may be understood as an acceptance of the validity of the rule or set of rules declared by the resolution by themselves. The principle of non-use of force, for example, may thus be regarded as a principle of customary international law […]⁶³

As regards the United States in particular, an expression of its stance towards the prohibition of the use of force was alleged to be found in some of its earlier verbal acts, such as its approval of a resolution condemning aggression adopted at the Sixth International Conference of American States (18 February 1928),⁶⁴ or its ratification of the Montevideo Convention on Rights and Duties of States (26 December 1933) whose Article 11 obliged States Parties not to recognize territorial acquisitions or special advantages which have been obtained by force.⁶⁵ In the same spirit, the acceptance by the US of the principle of the prohibition of the use of force, which was integrated in the 1975 CSCE Final Act’s Declaration of principles whereby the participating States had undertaken to “refrain in their mutual relations, as well as in their international relations in general” from the threat or use of force, was considered to constitute an evidence of its official position towards the legal prohibition of the inter-State use of force.⁶⁶ Thus, without examining actual State practice, the International Court of Justice held that the acceptance of the above non-binding declarations and resolutions, most of which had been worded in political—not even legal—terms, proved to a sufficient degree the existence of an opinio juris prohibiting the use of force in international relations.⁶⁷

This conclusion could not have been more dubious, for instead of reflecting upon appropriate State practice, the Court merely acknowledged the Parties’ verbal acts as evidence of customary international law. As a matter of fact, the provisions of General Assembly resolutions are not necessarily endowed with opinio juris—the psychological conviction that their rules do indeed reflect binding international law. As Nicholas Tsagourias recalled—by reference to H. Hart—States sometimes consent to rules either because they face popular “criticism and pressure,” or because the rules at issue are “not mandatory.”⁶⁸ In N. Tsagourias’ view, the General Assembly resolutions, in addition to their non-mandatory legal status under the UN Charter,⁶⁹ always are products of policy deals, concessions and political wrestling over the United Nations Member States’ national interests.⁷⁰ He also recalled, quite properly, H. W. A. Thirlway’s suggestion to the effect that, in order for a UN General Assembly resolution to be regarded as evidence of opinio juris, there should be “a sufficient body of state practice for the usage element of the alleged custom to be established without reference to the resolution.”⁷¹ However, the confusing statistics offered in the High Panel Report (see supra 2.1.2.2) lead one to conclude that the State practice with regard to the legal prohibition of the use of force is not either coherent or uniform. Besides, as N. Tsagourias suggested, the fact that States at times behave inconsistently with the General Assembly resolutions they consented to allows assuming that States sometimes vote in the General Assembly for what they believe international law “ought to be”—or might be in the future—and not for what it “actually is” at the present stage.⁷² The legal justifications for some of States’ modern practices in the area of the use of force are examined below, at 2.4.

1.3 Jus cogens Obligation

Whereas the treaty-based and customary nature of Article 2(4) has been considered above (see supra 2.1.1–2.1.2), it may also be useful to reflect on whether this provision—or at least some of its elements—also constitutes a jus cogens norm, a peremptory norm of general international law.⁷³ If this indeed is the case, the legal consequences of its breach should be more far-reaching than those of a breach of an “ordinary” conventional or customary rule of international law.⁷⁴ The jus cogens rules give rise to erga omnes obligations,⁷⁵ that is to say, their breaches affect the interests of larger groups of States—indeed, those of the international community of States as a whole⁷⁶—which suggests that international law should provide States with more compelling tools for reacting to such breaches, commensurate with their particular gravity.

The International Law Commission’s Articles on Responsibility of States for Internationally Wrongful Acts⁷⁷ (cf. supra 1.2.5.6) suggest, in Articles 40⁷⁸ and 41,⁷⁹ a number of important implications, if a State’s use of force in violation of Article 2(4) of the Charter were to be regarded as a breach of a peremptory norm of general international law, and not “merely” of treaty law or customary international law.⁸⁰ First, it follows from Article 40 of Articles on Responsibility of States that a breach by a State of an obligation arising under a peremptory norm of general international law can be “serious”—if it involves “a gross or systematic failure by the responsible State to fulfil the obligation”—and “less-than-serious,” logically, if the obligation in question is breached to a minor degree or not systematically.⁸¹ The UN Charter makes a formal distinction, in Article 39, between three types of breaches of obligations arising under Article 2(4): threats to the peace, breaches of the peace and acts of aggression—but does not contain any more specific normative or practical criteria for distinguishing between them. It appears that acts of aggression, as the most serious type of breaches in this classification, should of necessity fall within the ambit of Article 40 of the 2001 Articles,⁸² whereas threats to the peace or breaches of the peace, although breaching Article 2(4), might not necessarily reach this threshold of gravity. We will not tackle threats to the peace or breaches of the peace in much detail, for the sake of volume space, as they do not fall within the scope of this research. The definitional particulars of acts of aggression are dealt with below, at 2.3 and 5.1.1.2–5.1.1.3.

Second, States are required (“shall cooperate”)—not merely allowed or encouraged—to bring an end, by joint efforts, to any serious breach within the meaning of Article 40. Under current international law, such “lawful means” for suppressing acts of aggression—as the most serious breaches of the obligation arising under Article 2(4) of the UN Charter—include the suspension of rights and privileges under the Charter of the United Nations (Article 5), expulsion from the UN membership (Article 6), individual or collective self-defence (Article 51, see infra 2.4.1.1–2.4.1.4), collective enforcement action under the auspices of the Security Council (Chapter VII, see infra 2.4.1.5), or having recourse to regional security arrangements (Chapter VIII). The victim of a serious breach of an obligation arising under Article 2(4) of the UN Charter should not be left alone vis-à-vis the aggressor State(s). Instead, lawful means must be used to put an end to such an aggression as soon as possible.⁸³

Third, States are required to refrain from recognizing as lawful situations created by serious breaches of jus cogens, and from rendering aid or assistance in maintaining such situations. Acts of aggression can lead to a variety of unlawful results (see infra 4.1 and 4.5.1–4.5.4) most of which are, in one way or another, related to the victim State’s territorial integrity or political independence (cf. supra 2.1.1.1). As will be shown below at 2.1.3.2, States and relevant international bodies have, as a rule, indeed refrained from recognizing the legal validity of circumstances resulting from unlawful uses of force or from violations of the principle of self-determination of peoples (cf. infra 2.4.2.2), which most probably testifies to the respective rules’ status of jus cogens.

And last but not least, Article 41(3) mentions that serious breaches of obligations arising under jus cogens norms may also entail “further consequences” under international law. Assuming that Article 2(4) indeed constitutes jus cogens, one should think, among such further consequences, of a direct (see infra Chap. 5) or indirect (see infra 4.6.1 and Chap. 4) enforcement of individual criminal responsibility (see especially infra 5.2.4) of natural persons who would have contributed to the planning, preparation, initiation or execution of an act of aggression by a State (see infra 2.3 and 5.1.1.2–5.1.1.3). As will be discussed below (at 5.3.2.7 and 5.3.3), a determination by the Security Council that an act of aggression—a serious breach of an obligation arising under the hypothetical jus cogens provision contained in the Charter’s Article 2(4)—has been committed should predictably lead to the identification of individuals who caused that act to happen, and to the determination of their criminal responsibility for the act. Likewise, the ICC Prosecutor’s substantiated assumption about a State’s having committed an act of aggression—even without a plain determination to the effect by the Security Council—may, in appropriate circumstances, lead to the same consequences (see infra 5.3.2.8–5.3.2.9).

Having outlined the specific consequences that the most serious type of breach of Article 2(4) of the Charter of the United Nations—an act of aggression—would necessitate, if this Article were confirmed to constitute jus cogens, the suitability of attributing this status to Article 2(4) should now be examined. This analysis should help in the assessment of a lasting discrepancy between the Charter’s strongly worded prohibition of the use of inter-State force (see supra 2.1.1) and the actual, deplorably frequent, practice of its use (see supra 2.1.2.2). In other words, should State practices diverging, in serious ways, from Article 2(4) of the Charter be regarded as testifying to the emergence of new customary rules of international law on the inter-State use of force, or should they, instead, be viewed as serious breaches of obligations arising under a peremptory norm of general international law?

The 1969 Vienna Convention’s definition of a peremptory norm of general international law (jus cogens, see supra note 74) includes a number of elements whose consideration should be useful for the purpose of this research: (1) a norm in question must be accepted and recognized by the international community of States as a whole; (2) due to its overarching character, such a norm allows for no derogation in any circumstances; and (3) it is a norm of a lasting, system-building nature, for it can be modified only by a subsequent norm of general international law having the same character. To which extent does the prohibition of the use of force embodied in Article 2(4) of the Charter of the United Nations meet these criteria?

1.3.1 Acceptance and Recognition by the International Community of States as a Whole

Article 2(4) is, by and large, accepted and recognized by the international community of States as a whole. As a Principle of the United Nations, it is binding upon all United Nations Member States and, as was pointed out above (see supra note 4), Article 2(4) also provides protection to non-Members, without being formally binding upon them. It was relied upon in numerous acts adopted by international bodies—such as the United Nations General Assembly (see supra 1.2.5.3) or the CSCE/OSCE—and in decisions of the International Court of Justice (cf. supra 2.1.2.2–2.1.2.3). Yet, as was noted above at 2.1.2.2, the practice of applying Article 2(4) since 1945 has not always been consistent with such formal recognitions. States were breaching the prohibition, directly or indirectly, on a variety of grounds but most frequently invoking the right to individual or collective self-defence, which is referred to in the Charter’s Article 51 as a plain exception to the prohibition of the use of force (see infra 2.4.1.1–2.4.1.4). As was noted above (see supra 2.1.2.1), Article 51 does not itself regulate the implementation of this inherent right and necessitates further regulation by rules of customary international law—which creates space for (possibly selfish) interpretations of the provision. It may thus be concluded, somewhat paradoxically, that Article 2(4) is not contested by States verbally but is in fact breached, more often than could reasonably be expected from a Principle of the United Nations, as a matter of their practice.

1.3.2 Non-derogable Character

Now turning to the second criterion, one should ask whether there exist any specific (normative or practical) standards on whose basis one could differentiate between legitimate uses of force and “derogations” from Article 2(4)—which are not allowed, if that rule indeed constitutes one of jus cogens.⁸⁴ Clearly, the assertion of a legal title over territory by (armed) force (cf. supra 2.1.1.2 and infra 4.1.2, 5.2.2–5.2.3) is among such specific standards. According to Alexander Orakhelashvili—a recognized authority on jus cogens—since 1945, the prohibition of deriving legal title from illegal uses of force and breaches of the principle of self-determination did acquire the status of a peremptory norm of general international law.⁸⁵ In his important treatise on the subject, A. Orakhelashvili recalled the opinions of Sir Robert Yewdall Jennings (1913–2004) to the effect that a use of force might not result in the acquisition of title if it has been condemned as illegal,⁸⁶ and of Charles de Visscher (1884–1973)—that international law could not regard as lawful the benefits ensuing from the use of force, if it outlaws the use of force in an absolute way.⁸⁷ A. Orakhelashvili evoked further that several territorial changes had been regarded as null and void due to their conflict with the jus cogens norms: for instance, “Jordan’s occupation of East Jerusalem since 1948 was a violation of Article 2(4) of the UN Charter, and consequently Jordan was unable to acquire the sovereignty over that area,”⁸⁸ and “[t]he Israeli Occupation of the West Bank and East Jerusalem was similarly void for an identical reason.”⁸⁹ Consequently, he concluded that the corollaries of the said occupations⁹⁰ had not merely been denoted as “illegal”—they had been deemed null and void, that is to say, no legal effect could be derived from them ab initio.⁹¹ Therefore, despite the lapse of time, these territories are still referred to as occupied territories, and Israel as an occupying power.⁹² A. Orakhelashvili recalled that these unequivocal characteristics had been confirmed by the UN Security Council in Resolution 672 (1990) and by the ICJ in the 2004 Wall Advisory Opinion.⁹³ A. Cassese (1937–2011) explained these opinions of the key bodies of the United Nations in the following manner:

[A]t present general international law has departed markedly from the principle of effectiveness: de facto situations brought about by force of arms are no longer automatically endorsed and sanctioned by international legal standards. At present the principle of legality is overriding—at least at the normative level—and effectiveness must yield to it.⁹⁴

A. Orakhelashvili further stressed that the voidness of a forcible acquisition of territory should result in the nullity of juridical acts emanating from the unlawful exercise of sovereign powers in furtherance of that acquisition.⁹⁵ Thus, the International Court of Justice recalled in the Wall Advisory Opinion resolution 298 (1971) adopted by the Security Council on 25 September 1971 to the effect that “all legislative and administrative actions taken by Israel to change the status of the City of Jerusalem, including expropriation of land and properties, transfer of populations and legislation aimed at the incorporation oî the occupied section, are totally invalid and cannot change that status.”⁹⁶ The Court further recalled the Security Council Resolution 478 (1980) by which a provision in Israel’s Basic Law on the status of Jerusalem as the “complete and united” capital of Israel,⁹⁷ along with all measures “which have altered or purport to alter the character and status of the Holy City of Jerusalem,” were declared null and void.⁹⁸ The ICJ also recalled the UN Security Council’s attitude—expressed in resolution 446 (1979) of 22 March 1979—towards “the policy and practices of Israel in establishing settlements in the Palestinian and other Arab territories occupied since 1967” as being in flagrant violation of the provisions of the Fourth Geneva Convention relative to the Occupying Power’s rights and responsibilities,⁹⁹ especially Article 49.¹⁰⁰ The Court ruled that those measures were “without legal effect” and could not alter the status of these territories (including of East Jerusalem) as occupied territories, and the continued status of Israel as an Occupying Power was confirmed accordingly.¹⁰¹ In A. Orakhelashvili’s opinion, the peremptory prohibition of the use of force under international law was also relevant in the cases of East Timor¹⁰² and Northern Cyprus¹⁰³: ”[I]n all these cases the invalidity of titles as confirmed by the United Nations organs [was] implementing and declaratory of the jus cogens nullity, not just a discretionary action.”¹⁰⁴

To wrap up on the second criterion, one may suggest, by way of analogy, that, if the prohibition of the use of armed force against the territorial integrity or political independence of States and the principle of self-determination of peoples were found, both by the International Court of Justice and leading publicists, to constitute a peremptory norm of general international law (jus cogens), there should be little reason to oppose why the other fundamental values protected by Article 2(4)—such as “international co-operation in solving international problems of an economic, social, cultural, or humanitarian character, and in promoting and encouraging respect for human rights and for fundamental freedoms for all without distinction as to race, sex, language, or religion” (cf. Article 1(3) of the UN Charter)—as well as the other Purposes of the United Nations (cf. supra 2.1.1.1) might not be protected in a similar manner. If that were indeed so, the case for the legitimacy of “humanitarian intervention”—an international military tool to stop large-scale violations of fundamental human rights—could become a good deal stronger (see infra 2.4.3.2).¹⁰⁵

1.3.3 Normative Stability

As for the last criterion—that a jus cogens norm can be modified only by a subsequent norm of general international law having the same character—it seems to evoke no particular difficulty. It has been observed above (see note 11) that the conservative law regulating the use of force in international relations has experienced virtually no changes since the adoption of the Charter of the United Nations (cf. supra 1.2.5.1)—and no considerable revision of its text is to be expected in a foreseeable future, due to the complex technicalities of revising a treaty as system-building as the Charter.¹⁰⁶ For sure, Article 2(4) shall not be formally replaced by an alternative provision having the same status for decades to come—which means that States should have to adapt their conduct to its requirements, or else learn better interpreting its content—as a matter of putting the principle of legality into practice, to borrow from Antonio Cassese’s statement quoted above (at 2.1.3.2)—in their favor, in light of their conflicting practices. Whereas rules of customary international law can indeed be altered by the practice of States (cf. supra 2.1.2.2), a peremptory norm of general international law (jus cogens) cannot be modified by any contrary practice of States, for any contrary practice would itself constitute a breach of the norm in question. As the foregoing analysis suggests, there are sufficient grounds to believe that Article 2(4) of the UN Charter does constitute a peremptory norm of general international law, and aggression should be regarded as a serious breach thereof and entail both the responsibility of a delinquent State and the individual criminal responsibility of its authors, in the sense of Article 41(3) of the 2001 Articles on Responsibility of States for Internationally Wrongful Acts. A more detailed analysis of this assumption will now be offered.

2 Aggression as a Serious Breach of a Peremptory Norm of General International Law

As the Articles on Responsibility of States for Internationally Wrongful Acts were being drafted (cf. supra 1.2.5.6), there was an important debate within the International Law Commission as to whether and how the Articles should reflect the existence of a “hierarchy” of obligations arising under international law and, accordingly, one of breaches of those obligations (cf. supra 2.1.3).¹⁰⁷ The learned debate involved such contentious issues as the legal nature of international responsibility, the feasibility of imposing responsibility on sovereign States and of enforcing a collective “criminal liability” of States, the appropriateness of classifying States’ infractions as international delicts and international crimes, and the like.¹⁰⁸ A vast majority of the International Law Commission’s members favored the adoption of this two-level classification.¹⁰⁹ Hence, the Commission’s Special Rapporteur on International Responsibility, Roberto Ago (1907–1995), suggested, in 1976, a categorization of breaches of States’ international obligations under the headings of international crimes and international delicts:

• 1. An act of a State which constitutes a breach of an international obligation is an internationally wrongful act, regardless of the subject matter of the obligation breached.

• 2. An internationally wrongful act which results from the breach by a State of an international obligation so essential for the protection of fundamental interests of the international community that its breach is recognized as a crime by that community as a whole.

• 3. Subject to paragraph 2, and on the basis of the rules of international law in force, an international crime may result, inter alia, from:

  • (a) A serious breach of an international obligation of essential importance for the maintenance of international peace and security, such as that prohibiting aggression;

    […]

• 4. Any internationally wrongful act which is not an international crime in accordance with paragraph 2 constitutes an international delict.¹¹⁰

This proposal took into account post-War developments in international criminal law (see supra 1.2) inasmuch as it referred to aggression, in an explicit manner, among serious breaches of international obligations of essential importance for the maintenance of international peace and security (Article 19(3)(a)) and characterized these as international crimes (Article 19(2)). Even so, as the International Law Commission’s attitude towards the “criminal responsibility of the State” evolved over time, the final version of the Articles contained no reference to international crimes but dealt with less controversially worded “internationally wrongful acts” (Article 2) and “serious breaches of peremptory norms of general international law” (Article 40, cf. supra 2.1.3). Notably, the final edition of the Articles, unlike R. Ago’s earlier proposal, made no more specific mention of aggression and offered no other samples of serious breaches of international obligations. The effects of this omission are twofold: on the one hand, the formulation included in the Articles’ final edition is comprehensive enough to allow States to react, by lawful means, to a serious breach of any peremptory norm of general international law; on the other hand, the range of these norms has not been determined in a clear-cut manner and is capable of further development over time.¹¹¹ Although the prohibition of aggression is, under modern international law, among the least dubious of such norms, it does merit a supplementary test.

2.1 Aggression as a Serious Breach of an Obligation Arising Under Article 2(4) of the Charter of the United Nations

Comprehensive opinions favoring the qualification of the prohibition of the use of force under Article 2(4) of the UN Charter as a jus cogens norm are to be found in the official proceedings of international judicial and expert bodies, in States’ statements at international conferences,¹¹² and in the international legal doctrine (cf. supra 2.1.3).

2.1.1 Attitude of the International Court of Justice

The International Court of Justice observed in para 190 of the Nicaragua Judgment that Article 2(4) “is frequently referred to in statements by State representatives as being not only a principle of customary international law but also a fundamental or cardinal principle of such law.”¹¹³ This affirmative opinion took account of the official positions of both Nicaragua and the United States in the case:

Nicaragua in its Memorial on the Merits submitted in the present case states that the principle prohibiting the use of force embodied in Article 2, paragraph 4, of the Charter of the United Nations “has come to be recognized as jus cogens”. The United States, in its Counter-Memorial on the questions of jurisdiction and admissibility, found it material to quote the views of scholars that this principle is a “universal norm”, a “universal international law”, a “universally recognized principle of international law”, and a “principle of jus cogens”.¹¹⁴

The Court’s observation was echoed, in an even more assertive way, in the Separate Opinion of the President of the Court, Judge Nagendra Singh (1914–1988), who stated that “the principle of non-use of force belongs to the realm of jus cogens, and is the very cornerstone of the human effort to promote peace in a world torn by strife.”¹¹⁵

2.1.2 Attitude of the International Law Commission

The International Law Commission also dealt with the legal implications of the characterization of the prohibition of aggressive use of force as a jus cogens norm, especially in the course of the codification work on the Vienna Convention on the Law of Treaties. The Commission held that a peremptory norm of general international law forbidding aggressive use of force had already come into existence in 1945,¹¹⁶ which meant that any treaty designed to instigate aggression against another State made after the entry into force of the Charter would be invalid ab initio, and that any acts performed in reliance on such a treaty would be illegal. In its Commentary on Article 50 of its draft Articles on the Law of Treaties, the Commission reiterated its view that “the law of the Charter concerning the prohibition of the use of force in itself constitutes a conspicuous example of a rule in international law having the character of jus cogens.”¹¹⁷ The specific discussions on issues arising from the effects of aggression on treaties were concerned, inter alia, with the effects of the determination of an act of aggression on the treaty relations of an aggressor State,¹¹⁸ and the nature and validity of treaties concluded between the victorious States and vanquished aggressors (“case of an aggressor State”).¹¹⁹

In its Commentary on the 2001 Articles on Responsibility of States for Internationally Wrongful Acts, the International Law Commission has been even more assertive in pointing out the jus cogens character of the prohibition of aggression. Although not having provided any examples of peremptory norms of general international law in the Articles’ final text, the Commission did give such examples in its official Commentary on Article 40 (see supra 2.1.3). Having recalled that such practices as “slavery and the slave trade, genocide, and racial discrimination and apartheid […] have been prohibited in widely ratified international treaties and conventions admitting of no exception,”¹²⁰ the ILC reminded further the ICJ’s conclusions to the effect that the fundamental rules of international humanitarian law applicable in armed conflict were “intransgressible” in character and hence peremptory,¹²¹ and that “[t]he principle of self-determination [was] one of the essential principles of contemporary international law,” which gave rise to “an obligation to the international community as a whole to permit and respect its exercise.” ¹²² In the International Law Commission’s view, the prohibition of aggression under international law was likewise generally agreed to be regarded as peremptory, for a few reasons: it is consistent with every State’s “legal interest in the protection of certain basic rights and the fulfilment of certain essential obligations,”¹²³ constitutes an obligation erga omnes,¹²⁴ and serves the purpose of protecting “the survival of each State and the security of its people.”¹²⁵ As Article 40 of the 2001 Articles does not itself lay down any procedure for determining whether or not a serious breach of an obligation arising under a peremptory norm of general international law has been committed,¹²⁶ it is useful to look into the rules for attributing an act of aggression to a delinquent State.

2.2 Attribution of Aggression to a State Under International Law

The conduct of an organ of a State, or of a person or entity directed, instigated or controlled by a State, is usually attributed to that State.¹²⁷ This rule has acquired the character of a customary norm of international law.¹²⁸ In conformity with this recognized rule, Article 4 (“Conduct of organs of a State”) of the 2001 Articles reads:

• 1. The conduct of any State organ shall be considered an act of that State under international law, whether the organ exercises legislative, executive, judicial or any other functions, whatever position it holds in the organization of the State, and whatever its character as an organ of the central Government or of a territorial unit of the State.

• 2. An organ includes any person or entity which has that status in accordance with the internal law of the State.

As the International Law Commission pointed out, “[a]s a normative operation, attribution must be clearly distinguished from the characterization of [a State’s] conduct as internationally wrongful.”¹²⁹ The distinctive task of attribution is to establish whether an act in question is an act of the State for the purpose of responsibility, and this can be done by showing that an internationally wrongful act—or, for the purpose of this research, an alleged act of aggression in the quality of a serious breach of an obligation arising under a jus cogens norm, Article 2(4) of the Charter—committed by a State derived from an act performed by an organ of that State.¹³⁰ Since international law does not, as a rule, govern the internal organization of States and the functions of their organs, the domestic law and practice of each State are crucial in determining what constitutes an organ for the purposes of responsibility. In particular, the power to declare a war or, more generally, to engage a State in an international armed conflict is usually possessed by the executive or the legislature, or else is divided between these branches—hence the potential authors of a hypothetical act of aggression are to be sought, first and foremost, among officials belonging to these categories (cf. infra 4.2.1–4.2.3). However, whereas each State certainly determines its internal structure and functions through its own laws and practices, international law does have a role to play, as far as States’ war-making functions (in both jus ad bellum and jus in bello) are concerned: it should be recalled that “the characterization of an act of a State as internationally wrongful is governed by international law,” and that “such characterization is not affected by the characterization of the same act as lawful by internal law.”¹³¹ Consequently, any decision to use military force against another State, even if has been taken in accordance with an initiator State’s appropriate domestic laws and procedures, must be tested in light of applicable international law, with due regard to the jus cogens character of Article 2(4) of the UN Charter. Applicable thematic sources, such as the 1974 Definition of Aggression, may be helpful for this purpose, as interpretative tools.

3 Elements of an Act of Aggression Under the 1974 Definition of Aggression

The General Assembly resolution 3314 (XXIX) was adopted on 14 December 1974, as an interpretation of Article 2(4) of the UN Charter, with a Definition of Aggression annexed to it¹³² (cf. supra 1.2.5.3). Constructed, to a substantial extent, upon the draft definition of aggression proposed by the Soviet Union in 1933 (see supra 1.1.6.6) and upon alternative drafts suggested by the USSR and groups of Western and developing States during the 1950s and 1960s,¹³³ the new definition was adopted, almost thirty years after the entry into force of the UN Charter, as a guideline for the Security Council’s determination of the existence of an act of aggression¹³⁴ and was generally (albeit not universally) recognized.¹³⁵ A useful interpretative instrument, the Definition—as a General Assembly resolution—was not legally binding and allegedly had “no visible impact” on the subsequent practice of the Security Council,¹³⁶ probably, due to the two major blocks’ political confrontation in the Cold War.¹³⁷ Yet, although the Definition had lacked a binding force and suffered from a number of structural and substantial deficiencies, it is worth considering here in some detail, as it did exercise a considerable impact on the drafting of the Rome Statute’s definition of the crime of aggression (see infra 5.1.1.3).

3.1 “Chapeau” of the Definition

The 1974 Definition contains a general part followed by an incomplete list of examples of acts of aggression. The general part of the Definition (Article 1) reads as follows:

Aggression is the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations, as set out in this Definition.

Yoram Dinstein singled out six essential distinctions between this formula and the primary rule articulated in Article 2(4) of the Charter of the United Nations (cf. supra 2.1.1): “(i) the mere threat of force is excluded; (ii) the adjective ‘armed’ is interposed before the noun ‘force’; (iii) ‘sovereignty’ is mentioned together with the territorial integrity and the political independence of the victim State; (iv) the victim is described as ‘another’ (rather than ‘any’) State; (v) the use of force is proscribed whenever it is inconsistent with the UN Charter as a whole, and not only with the Purposes of the United Nations; (vi) a linkage is created with the rest of the Definition.”¹³⁸ It has been suggested that the adding of a number of elements to the definition of aggression was just intended to raise the assessment threshold and accordingly to do away with the possibility of invoking shooting “a few stray bullets across a boundary” as the commission of an act of aggression by a State.¹³⁹ Yet, the normative and practical influence of this major—indeed, progressive—development in international law could have been more far-reaching. Its more precise wording, in comparison with Article 2(4) of the Charter, could have made the Definition a workable tool for the protection of sovereign interests of individual States and for the maintenance of international peace and security, and so would have reinforced the impact of Article 2(4) itself. The chief problem with the Definition was its recommendatory status of an annex to a General Assembly resolution.¹⁴⁰ If the Definition had been bestowed with a proper adequate legal force—for instance, by way of approval by the Security Council whose decisions are mandatory for all Members of the United Nations¹⁴¹ and the carrying out of whose foremost function¹⁴² the Definition was intended to facilitate—it would have become a “harder” source of international law and should have been complied with by States in a more consistent manner.

3.2 Examples of Acts of Aggression

In furtherance of the general part, Article 3 of the Definition lists possible examples of acts of aggression, regardless of their being accompanied by a declaration of war:

(a) The invasion or attack by the armed forces of a State of the territory of another State, or any military occupation, however temporary, resulting from such invasion or attack, or any annexation by the use of force of the territory of another State or part thereof;

(b) Bombardment by the armed forces of a State against the territory of another State or the use of any weapons by a State against the territory of another State;

(c) The blockade of the ports or coasts of a State by the armed forces of another State;

(d) An attack by the armed forces of a State on the land, sea or air forces, or marine and air fleets of another State;

(e) The use of armed forces of one State which are within the territory of another State with the agreement of the receiving State, in contravention of the conditions provided for in the agreement or any extension of their presence in such territory beyond the termination of the agreement;

(f) The action of a State in allowing its territory, which it has placed at the disposal of another State, to be used by that other State for perpetrating an act of aggression against a third State;

(g) The sending by or on behalf of a State of armed hands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount to the acts listed above, or its substantial involvement therein.

Notably, each subparagraph of Article 3 refers to an action performed by or on behalf of a State, thereby confirming that aggression is an internationally unlawful act of State committed against another State. The list is quite comprehensive (cf., however, infra 5.1.1.3.8), probably with one exception consisting in that subparagraphs (a) and (b) seem to be somewhat repetitive, for it is difficult to imagine how an “attack by the armed forces of a State of the territory of another State” (subparagraph (a), cf. infra 5.1.1.3.1) can be carried out without “the use of any weapons” referred to in subparagraph (b) (cf. infra 5.1.1.3.2),—as was discussed above (under 2.1), the word “attack” implies its military character and, consequently, the use of weapons.¹⁴³ On the other hand, the “[b]ombardment by the armed forces of a State against the territory of another State or the use of any weapons by a State against the territory of another State” is well possible without “the invasion or attack by the armed forces of a State” prohibited under subparagraph (a), and the singling out of bombardment or the use of weapons as a separate type of aggression is therefore justified.

Out of these, only the last subparagraph was explicitly pronounced by the International Court of Justice to be declaratory of customary international law (cf. infra 5.1.1.3.7).¹⁴⁴ Yoram Dinstein maintains, however, that, possibly, the other portions of the 1974 Definition’s Article 3 may too be regarded as being indicative of “harder” rules of international law than the General Assembly resolutions are as a rule.¹⁴⁵ As a matter of fact, the Nicaragua case is not an apposite source to look for the attitude of the ICJ towards the issue in question, for in that case, the Court could not practically examine whether subparagraphs (a)–(f) of Article 3 were reflective of customary international law, because the factual basis of the case was limited to subparagraph (g).¹⁴⁶ The absence of the Court’s jurisprudence on subparagraphs (a)–(f) of the 1974 Definition’s Article 3 should therefore not be interpreted as the ICJ’s unambiguously disapproving or doubtful attitude towards their substance but simply as a matter of fact that the Court did not yet have an opportunity of scrutinize their legal force in light of customary international law.

3.3 Non-Exhaustive Character of the List

Another problem about the international legal value of the 1974 Definition is that its Article 3 is not exhaustive, and the Security Council may itself determine what other international uses of force may amount to aggression.¹⁴⁷ This autonomy of political appraisal accorded to the Council is indeed warranted in the light of its required operational flexibility as an international organ primarily charged with the maintenance of international peace and security (see supra note 143). Yet, the legal qualification of uses of force as acts of aggression, in order for them to necessitate specific consequences for States and individuals under applicable international law (see supra 2.2.1.2), should involve more strictly defined assessment criteria and a less politicized procedure than the Security Council’s is. As the Rome Statute’s definition of an individual crime of aggression contains a direct reference to the 1974 Definition (see infra 5.1.1.2–5.1.1.3), one must note that the ICC Statute’s Article 8 bis (2)—unlike its “parent provision”—is exhaustive, in accordance with the principle of legality (nullum crimen sine lege) established in ICL. Whilst the Security Council may indeed “determine that other acts [than only those listed in Article 3 of the 1974 Definition may] constitute aggression under the provisions of the Charter,”¹⁴⁸ the ICC Statute does not allow for such an extensive interpretation of elements of individual crimes within its jurisdiction (see infra 5.2.1).

3.4 The Problem of the “First Use” of Force

In accordance with Article 2 of the 1974 Definition, the first use of armed force by a State in contravention of the Charter of the United Nations constitutes prima facie evidence of an act of aggression, although the Security Council may, in conformity with the Charter, conclude that a determination that an act of aggression has been committed would not be justified in the light of other relevant circumstances, including the fact that the acts concerned or their consequences are not of sufficient gravity.¹⁴⁹ It appears that the reference to the first use of armed force should be read in connection with the essential circumstance that follows, namely, that such first use of armed force must be “in contravention of the Charter.” It is conceivable that a State uses minor force against another State in the first instance but the target State responds to the trivial incident in a disproportionately forceful fashion and thus—in overreaction—itself violates the Charter. In such a case, the target State might itself probably be found guilty of committing aggression¹⁵⁰ (cf. infra 4.3.1.1.2). It must have been for this reason that the first use of force is not as such referred to in the Rome Statute’s Article 8 bis but the major qualification of the potentially aggressive use of armed force—namely, its use in manifest violation of the Charter of the United Nations—is integrated in the provision (cf. infra 5.1.1.1.5). It would then be up to appropriate international organs to assess on a case-by-case basis (cf. infra 5.3.2.7–5.3.2.9, 5.3.3) whether it was the first actual use of force or a forceful response thereto that would have been in manifest violation of the Charter and hence would have constituted an act of aggression.

3.5 The Discretionary Power of the UN Security Council

In accordance with the Charter, the primary power to determine acts of aggression rests with the Security Council.¹⁵¹ Yet, in many instances, even the manifestly hostile behavior of States was not qualified as acts of aggression (see supra 1.2.5.2). The motivation behind such a restrictive application of the concept of aggression must have been far from purely legal: the Security Council is an international political body in whose action interests of its members—especially of permanent members—prevail,¹⁵² and it may not be expected to apply rules of international law in the same impartial way as a judicial body—such as the International Court of Justice or the International Criminal Court—should have to.¹⁵³ It may be asserted with a good degree of certainty that the normative standards for the determination of aggression listed in Article 3 of the 1974 Definition were not often used by the Security Council due to political and procedural circumstances, and not necessarily due to that Article’s inherent substantive deficiencies.

By contrast, these provisions should, hopefully, become more workable in the future practice of the International Criminal Court. Although the content of Article 8 bis (2) of the Rome Statute was drawn literally from Article 3 of the 1974 Definition of Aggression (see infra 5.1.1.3), and Article 8 bis (2)—probably, unnecessarily—made an explicit mention of the General Assembly resolution 3314 (XXIX) (see infra 5.1.1.2), the verbatim integration of these provisions in the Rome Statute as a matter of its own content should elevate them from the rank of “soft law” to the level of treaty law binding upon an increasing number of States Parties to the Statute, once Article 8 bis enters into force (see infra 5.1.2), and the Security Council might not ignore this development (see infra 5.3.2.7–5.3.2.9, 5.3.3).

4 Exceptions to the Prohibition of the Use of Force

It may be inferred from the foregoing analysis (cf. supra 2.1–2.3) that any use of force in inter-State relations not expressly authorized by international law would constitute a breach of Article 2(4) of the Charter of the United Nations, and the most serious breaches of an obligation arising under this jus cogens provision may be found to constitute aggression. Hence, an examination of lawful exceptions to the imperative prohibition of the use of force is required, to help identify acts, which do not, as a matter of current or emerging international law, qualify as aggression and, consequently, cannot entail States’ responsibility under international law and individuals’ liability under international or national criminal law. On the other hand, it may be assumed that any inter-State use of force, which cannot be justified by one of the lawful exceptions analyzed below, might constitute an act of aggression and should be subjected to an appropriate judicial scrutiny. This section will examine three categories of exceptions to Article 2(4): the Charter-based exceptions, i.e. ones explicitly mentioned in the UN Charter; the Charter-related exceptions, which are not explicitly mentioned in the UN Charter but have been inferred from its pertinent provisions by international organs; and, last but not least, extra-Charter exceptions, which derive from extra-Charter sources of international law.

4.1 Charter-Based Exceptions

The Charter of the United Nations allows explicitly only for two exceptions to the prohibition of the use of force—States’ “inherent” right of individual or collective self-defence (Article 51) and collective security measures under Chapter VII (Articles 39–50).¹⁵⁴ Both legal regimes will be considered in turn.

4.1.1 Individual or Collective Self-Defence: General Observations

As was noted by Oscar Schachter, at the origin of States’ inherent right of self-defence¹⁵⁵ there stood two principal schools of thought—the natural law school represented, inter alia, by Hugo Grotius (cf. supra 1.1.2.4), and the realpolitik school represented by practitioners such as the US Secretary of State Dean Gooderham Acheson (1893–1971).¹⁵⁶ According to the natural law school, States’ right of self-defence is intrinsic in their nature and may be invoked in a variety of circumstances—ranging from “an extreme circumstance of self-defence”¹⁵⁷ to routine situations below the threshold of life-or-death existential emergencies. In other words, in the opinion of the natural law scholars, the exercise by a State’s of its right of self-defence should be regarded as its regular and legitimate function, among such other functions—such as the maintenance of law and order, the regulation of its internal and external affairs, the emission of currency, and the like.¹⁵⁸ At the same time, as a technique of self-help—which, according to Yoram Dinstein, is typical to all primitive legal systems, including international law¹⁵⁹—individual or collective self-defence was quite beyond the confines of law.¹⁶⁰ Since—especially before the First World War but also between two World Wars (see supra 1.1)—any State might, in principle, resort to war against any other State, the quality of self-defence as a legal concept was rather limited. In the words of Eduardo Jiménez de Aréchaga (1918–1994), self-defence essentially “was not a legal concept but merely a political excuse for the use of force.”¹⁶¹ This actual state of affairs allowed representatives of the realpolitik school, in their turn, to conceive of States’ right of self-defence in terms of “power,”¹⁶² not of law—a view that might prevail until the entry into force of the Charter of the United Nations, with due regard to its Articles 2(4) (see supra 2.1) and 51 (see infra 2.4.1.1.1–2.4.1.1.5). It appears that, already in the inter-war period, a decisive argument in favor of the legal nature of the right of self-defence—suitably recalled by O. Schachter—was put forward by Sir Hersch Lauterpacht (1897–1960) in his seminal treatise The Function of Law in the International Community: “It [the right of self-defence] is regulated to the extent that it is the business of the courts to determine whether, how far, and for how long, there was a necessity to have recourse to it.”¹⁶³ In point of fact, it would make no sense to refer to self-defence as a State’s right under international law, if a State using armed force, allegedly, in self-defence were not willing or prepared to justify its military action in terms of such international law as may be applicable. H. Lauterpacht’s opinion was recalled in the Nuremberg Tribunal’s Judgment (for details, see infra 3.1.1),¹⁶⁴ and the Tribunal itself confirmed that “whether action taken under the claim of self-defence was in fact aggressive or defensive must ultimately be subject to investigation or adjudication if International Law is ever to be enforced.”¹⁶⁵

4.1.1.1 Article 51 of the Charter of the United Nations

As a matter of conventional international law, the general conditions under which States may resort to force in self-defence are specified in Article 51 of the Charter of the United Nations:

Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security.

Whereas it may be agreed that Article 51 does not indeed represent an exhaustive regulation of States’ right of self-defence under modern international law (cf. supra 2.1.2.1), it is submitted that it does constitute a suitable and overarching conventional framework for the exercise of this right’s customary elements, which “fill” and complement the framework but do not replace it as such.¹⁶⁶ An outline of the main elements of Article 51 is offered below.

4.1.1.2 “Nothing in the present Charter shall impair the inherent right […]”

The opening language of Article 51 confirms the inviolability of a State’s right of self-defence as a matter of principle. The right of self-defence is referred to as “inherent”—in line with the natural law theory recalled above—and is placed in a relatively superior position with respect to the other provisions of the Charter (“Nothing in the present Charter shall impair […]), i.e. the right of self-defence, if exercised by a State in good faith, appears to stand above any other rule of the Charter.¹⁶⁷ The exercise of the right, though, is subject to two cumulative conditions (see infra 2.4.1.1.4–2.4.1.1.5).

4.1.1.3 “[… O]f individual or collective self-defence […]

It is presumed that the term “self-defence” means recourse to armed or military force (cf. supra 2.1.1.2.1–2.1.1.2.2 and infra 2.4.1.1.4),¹⁶⁸ and does not, for the purpose of Article 51, directly cover non-military (e.g. diplomatic, economic, etc.) measures, which of course may too be used—as subsidiary tools¹⁶⁹—in order to restore the security of a State or States under attack. A State may exercise its right of self-defence individually or collectively with other States, whereby the collective exercise of the right may be more or less formalized—respectively, under the auspices of regional security organizations (e.g. NATO, CSTO, etc.) or else in the format of temporary international coalitions formed for the purpose of specific operations.¹⁷⁰

4.1.1.4 “[I]f an armed attack occurs against a Member of the United Nations […]”

It formally appears from this formula that Article 51 protects only Members of the United Nations. However, the “inherent” nature of States’ right of self-defence (see supra 2.4.1.1.2) as well as the applicability of the UN Charter’s more general regulations on the use of force to all States, including non-Members (see supra 2.1.1.1) lets one conclude that the Charter recognizes, as a matter of fact, any State’s right of self-defence, on the condition that the State is subjected to an armed attack. Two key issues are worthy of noting in this regard. First, the right of self-defence must be understood as a lawful reaction only to an armed attack—i.e. the employment by a State of its regular armed forces (in a broad sense currently accepted in international law), or of irregular armed groups (cf. supra 2.1.1.2.1), and of means and methods of warfare (in the sense of applicable international humanitarian law) against another State, its nationals, public or private property (cf. supra 2.1.1.2), or the employment of such physical force by a non-State actor as would result in effects comparable to those of an armed attack (cf. supra 2.1.1.2.2). In the sense of Article 51, no other factor may justify the use of armed force in self-defence.¹⁷¹ Second, there exists a substantial controversy among scholars regarding the admissibility of anticipatory (preventive, pre-emptive or interceptive) self-defence in the case of an imminent danger of an armed attack. For the purpose of this research, the issue will be dealt with below, at 2.4.1.2–2.4.1.4, in more detail. It suffices to mention here that competent international courts—in the first place, the International Court of Justice—did not yet pronounce themselves on the matter,¹⁷² although it was maintained in at least one dissenting opinion that Article 51 should not confine States’ right of self-defence to cases “if, and only if an armed attack occurs.”¹⁷³

4.1.1.5 “[U]ntil the Security Council has taken measures necessary to maintain international peace and security”

It follows from the concluding clause of Article 51 that the Security Council must take measures to maintain international peace and security, if an armed attack occurs against a Member of the United Nations. The nature of these measures is considered below, at 2.4.1.5. It may appear from the language that the right of self-defence ceases, once the Security Council has taken the required measures.¹⁷⁴ It is submitted, though, that in practice a State may continue exercising its right of self-defence until the full restoration of international peace and security, with due regard to its “inherent” (cf. supra 2.4.1.1.2) and, consequently, inalienable nature.

4.1.2 Preventive Self-Defence

Since the end of the Second World War (cf. supra 1.2 and infra 3.1.1–3.1.3), there has only been a limited State practice favoring the legitimacy of preventive self-defence.¹⁷⁵ A notable case—appropriately recalled by M. Kinacioglu¹⁷⁶—was Israel’s attack, in 1981, against an Iraqi nuclear reactor under construction, on the purported ground that it would be used for producing material for nuclear weapons, which Iraq would employ for attacking Israel. The circumstances of the case were considered by the Security Council,¹⁷⁷ and the Israeli action was unanimously condemned: “[T]he military attack by Israel [was] in clear violation of the Charter of the United Nations and the norms of international conduct.”¹⁷⁸ The Security Council members’ views about the legitimacy of preventive self-defence as such were thereby divided.¹⁷⁹

Dieter Wiefelspütz suggested defining preventive self-defence as “repelling an attack, which is not immediately challenging or threatening, or repelling a danger, which is not at hand.”¹⁸⁰ This author shares D. Wiefelspütz’s opinion to the effect that the absence of an identifiable threat or danger should render preventive self-defence internationally unlawful, unlike pre-emptive self-defence (see infra 2.4.1.3) whose legitimacy under international law—although not completely undisputed—is more well-founded.¹⁸¹ With due regard to the “Webster formula,”¹⁸² it appears that the preventive self-defence theory does not indeed meet the normative criteria laid down in Article 51 of the Charter of the United Nations (see supra 2.4.1.1.1–2.4.1.1.5) and should be discarded.

4.1.3 Pre-emptive Self-Defence

Especially after 11 September 2001 (cf. supra 2.1.1.2.1), the United States has been the world’s foremost promoter of the concept of pre-emptive self-defence.¹⁸³ In the 2002 National Security Strategy to Combat Weapons of Mass Destruction, President George W. Bush declared as follows:

United States military force and appropriate civilian agencies must have the capability to defend against weapons of mass destruction-armed adversary, including in appropriate cases through pre-emptive measures. This requires capabilities to detect and destroy an adversary’s weapons of mass destruction assets before their weapons are used […] The primary objective of a response is to disrupt an imminent attack or an attack in progress, and eliminate the threat of future attacks.¹⁸⁴

This statement only received a limited support among international lawyers, not least because in its concluding sentence, three essentially different legal regimes (interceptive self-defence, pre-emptive self-defence and preventive self-defence) had been put together in a manner, which is inappropriate from the point of view of applicable international law, under the same umbrella. Notably, even the closest ally of the United States in the “global war against terror”—the United Kingdom—expressed reservations about the notion of pre-emptive self-defence. The British Foreign Secretary commented on the issue as follows:

The issue of pre or post–pre-emption in respect of Iraq, I do not quite see the relevance. The issue is that here you have a regime which is in clear breach of an endless number of Security Council Resolutions requiring them to do certain things under Chapter VII […]¹⁸⁵

Pre-emptive self-defence stands for a State’s military action against potential adversary (usually, another State) in expectation of a hypothetical armed attack.¹⁸⁶ Pre-emptive self-defence differs both from preventive (see supra 2.4.1.2) and interceptive (see infra 2.4.1.4) self-defence in that its political constituent is indeed oriented towards a more or less defined potential threat, but the relevant military action is devoid, in a strict sense, of a prima facie defensive quality. The main justification the supporters of pre-emptive self-defence put forward is the imperfection of the Security Council’s decision-making procedure (cf. supra 1.2.5.2 and 2.3.5), whereby the Council’s permanent members and their allies are protected against any possible enforcement action (see infra 2.4.1.5). However, this is not completely true. As the example of the Security Council resolution 487 (1981) shows (see supra 2.4.1.2, especially note 179), even the closest allies of permanent Security Council members are not entirely immune from condemnation under the UN Charter (whereas the permanent members themselves indeed are). Furthermore, however flawed the Council’s procedure may be, the Charter’s rule to the effect that non-defensive uses of military force are only allowed for the purpose of enforcing relevant Security Council decisions (see infra 2.4.1.5), which have been taken on behalf of all Members of the United Nations,¹⁸⁷ remains valid—and, in that sense, the United States-led coalition’s invasion of Iraq in 2003 was clearly unlawful. In the aftermath of the invasion, an overwhelming majority of States opposed the United States’ conduct decisively, asserting, on the one hand, that the eradication of the Security Council’s primary authority in dealing with situations threatening international peace and security¹⁸⁸ would denote the end of collective supervision over the international use of force and, eventually, of multilateralism in the post-World War II international relations¹⁸⁹ (cf. supra 1.2), and, on the other hand, that a reintroduction of States’ liberty to resort to military action unilaterally would be unwarranted under modern international law.¹⁹⁰ In other words, such a reintroduction would put an end to the entire contemporary normative and institutional system of maintaining international peace and security. As Christopher Greenwood correctly observed, there must be a point beyond which self-defence ceases to be an exception to the prohibition of the use of force under international law and itself becomes plainly inconsistent with this prohibition.¹⁹¹

4.1.4 Interceptive Self-Defence

Unlike in the context of anticipatory self-defence (see supra 2.4.1.2–2.4.1.3), interceptive self-defence is resorted to when the danger of an armed attack against a State is grave, imminent and unmistakable. The nature of interceptive self-defence was illustratively explained by Yoram Dinstein:

Let us assume hypothetically that the Japanese carrier striking force, en route to the point from which it mounted the notorious attack on Pearl Harbor in December 1941, had been intercepted and sunk by the US Pacific Fleet prior to reaching its destination and before a single Japanese naval aircraft got anywhere near Hawaii. If that were to have happened, and the Americans had succeeded in aborting an onslaught which in one fell swoop managed to change the balance of military power in the Pacific, it would have been preposterous to look upon the United States as answerable for inflicting an armed attack upon Japan […]

Had the Japanese striking force been destroyed on its way to Pearl Harbor, this would have constituted not an act of preventive war but a miraculously early use of counter-force. To put it in another way, the self-defence exercised by the United States (in response to an incipient armed attack) would have been not anticipatory but interceptive in nature. Interceptive, unlike anticipatory, self-defence takes place after the other side has committed itself to an armed attack in an ostensibly irrevocable way. Whereas a preventive strike anticipates an armed attack that is merely ‘foreseeable’ (or even just ‘conceivable’), an interceptive strike counters an armed attack which is ‘imminent’ and practically ‘unavoidable’. It is the opinion of the present writer that interceptive, as distinct from anticipatory, self-defence is legitimate even under Article 51 of the Charter.¹⁹²

It is only possible to agree with Yoram Dinstein’s conclusion. Indeed, it would be unwise on the part of a potential victim State to wait for a fatal blow (“armed attack” in the sense of Article 51 of the UN Charter), which would incapacitate or severely harm that State’s defensive potential. If the aggregate of circumstances at a given time¹⁹³ leaves no doubt as to the impending attack, the potential victim State(s) should be entitled—by virtue of Article 51 of the Charter—to intercepting the attack by offering a targeted and proportionate military reaction. As was discussed above (at 2.4.1.1), though, a State exercising its right to self-defence in an interceptive manner must be prepared to justify its conduct in a court of law. Importantly, “[t]he invocation of the right to self-defence must be weighed on the ground of the information available (and reasonably interpreted) at the moment of action, without the benefit of post factum wisdom.”¹⁹⁴

4.1.5 Collective Security Measures Under Chapter VII

Unlike the mechanism of individual or collective self-defence examined above at 2.4.1.1–2.4.1.4, which is designed against “outside” aggression, the collective security mechanism is—in the words of Y. Dinstein—“introverted” in the sense that it is there to employ force against aggressors from within the system.¹⁹⁵ The principal difference between these mechanisms is that self-defence is exercised at the discretion of a State or States, against which (armed or physical) force has been employed (cf. supra 2.1.1.2), and collective security is founded upon the centralized authority of an organ of the international community—the Security Council of the United Nations (cf. supra 1.2.5.2).¹⁹⁶

The United Nations’ collective security system is set out in Chapter VII of its Charter (Articles 39–51). It follows from Article 39¹⁹⁷ that the Security Council’s functions in this domain are both preventive and restorative. As Yoram Dinstein put it:

The notion of maintaining international peace and security has a preemptive thrust. The purpose is to ensure, before it is too late, that no breach of the peace will in fact occur. Measures taken by the Council to forestall a breach of international peace and security have deterrence and prevention as their goals. Once a breach of international peace and security occurs (notwithstanding any prophylactic measures that may have been taken), the situation changes dramatically. At this point, the Council’s mission is to restore the peace. It has to take steps calculated to re-establish international law and order.¹⁹⁸

Pursuant to Article 39, the Security Council can make non-mandatory recommendations or take binding decisions, in order to propel action by the Member States of the United Nations. A grammatical interpretation of Article 39 suggests that measures of a non-military and military nature—listed, respectively, in Articles 41 and 42—are associated with mandatory decisions rather than with recommendations.¹⁹⁹ Let us succinctly consider non-military and military measures provided for in Chapter VII.

4.1.5.1 Non-military Measures

Article 41 of the Charter deals with non-military measures and reads as follows:

The Security Council may decide what measures not involving the use of armed force are to be employed to give effect to its decisions, and it may call upon the Members of the United Nations to apply such measures. These may include complete or partial interruption of economic relations and of rail, sea, air, postal, telegraphic, radio, and other means of communication, and the severance of diplomatic relations.

Notably, this list is not exhaustive (“[the measures] may include […]”), and the Security Council may itself decide which other measures not involving the use of force may be employed.²⁰⁰

4.1.5.2 Military Measures

As was discussed above (at 1.2.5.2), the Security Council became noticeably more functional in matters of maintaining international peace and security after the end of the “Cold War.” Chapter VII of the Charter was invoked, as a whole, in a number of resolutions adopted by the Security Council, as were some of its specific Articles.²⁰¹ Nevertheless, as was observed in the UN Secretary-General’s report entitled An Agenda for Peace (cf. supra 1.2.5.5), the key provision in Chapter VII, Article 42,²⁰² was not used, due to the absence of special agreements required by Article 43, and alternative means had to be sought. The same discord among the permanent Security Council members that rendered impossible the conclusion of special agreements under Article 43 did also cause the invalidity of Article 106 of the Charter and the ineptitude of the Military Staff Committee provided for under Article 47. Therefore, over time, two principal alternative mechanisms have developed—peacekeeping and non-Article 42 peace-enforcement.

The functional modalities of both mechanisms have been well summarized in Yoram Dinstein’s classic monograph.²⁰³ To borrow from his terminology, the principal function of a peacekeeping force is that of a “cordon sanitaire”—to physically separate parties to a conflict and to prevent further clashes.²⁰⁴ All peacekeeping forces—unlike forces set up for peace-enforcement—are established and maintained with the consent of all States concerned and are normally not authorized to employ military force, except in self-defence.²⁰⁵ Peacekeeping forces are usually—although not always—associated with the United Nations and are made up of national contingents supplied by the UN Member States.²⁰⁶ Thus, as an aggregate of representatives of national armed forces with an international mandate, peacekeeping forces have a dual legal status:

[T]he commander of the United Nations force is head in the chain of command and is answerable to the United Nations. The functions of the force as a whole are international. But its individual component forces have their own national duty and discipline and remain in their own national service.²⁰⁷

It must also be noted that members of the UN peacekeeping forces are bound to comply with the fundamental principles and rules of international humanitarian law when they use force in self-defence.²⁰⁸

In turn, as Yoram Dinstein put it, peace-enforcement is a practical way for getting round Article 42 of the Charter in the absence of special agreements provided for in Article 43.²⁰⁹ Since the 1990s, the Security Council has been authorizing individual or collective military actions by the UN Member States (instead of imposing a duty upon them to engage in such actions), in order to enforce its resolutions.²¹⁰ The Operation Desert Storm (1990) is broadly regarded as a “revolutionary development” and “the catalyst for fundamental change in the international regulation of the use of force.”²¹¹ The ensuing operations in Somalia (1992), Rwanda (1994), the former Yugoslavia (1994–1995),²¹² Haiti (1994²¹³ and 2004), Albania (1997),²¹⁴ the Central African Republic (1997), East Timor (1999),²¹⁵ Liberia, the Democratic Republic of the Congo,²¹⁶ and Côte d’Ivoire (2003), Kosovo (1999), Afghanistan (2001–2014), Iraq (2003–2011),²¹⁷ Chad (2007) and other actions followed in the novel trend. In carrying out the peace enforcement operations, the Security Council largely relied upon regional arrangements dealt with in Chapter VIII of the Charter (Articles 52–54).²¹⁸ The level of success in those operations has not been consistent. Besides, as Christine Gray observed, the policy of involving regional arrangements²¹⁹ might not be free from ulterior motives (cf. the principle of good intentions dealt with above at 1.1.2.3):

There is […] a danger that interested states operating under UN authorization would gain legitimacy to further their own interests. The early tradition of not using the forces of permanent members of the Security Council or of those states with geographical or historical interests in the state concerned has been further circumvented through this type of operation. Thus it was the USA that led the 1994 and 2004 operations in Haiti, France in Rwanda and the Central African Republic (1997), Italy in Albania, and Australia in East Timor. There was some suspicion of the motives of these states. In Rwanda Operation Turquoise was criticized for providing a safe haven for the perpetrators of genocide. These were, however, all temporary, limited forces operating with the consent of the host states even where this was not expressly indicated in the relevant resolutions. It is not clear that the use of the EU to lead an operation instead of a single member state will necessarily meet this concern as to ulterior motives. There were newspaper reports that the use of the EU in the DRC was interpreted by some as evidence of foreign state support for the incumbent President in the elections. And Chad seems to have regarded an EU force led by its former colonial power and current supporter, France, as more acceptable than a UN force.²²⁰

It is obvious that, at the present stage of affairs, “[c]lear divisions have emerged between those states claiming to act on behalf of the international community and those who reject such claims in the absence of express Security Council authorization of force”²²¹ The latter group of States suggests that the United States, the United Kingdom and some other States have gone too far in their interpretation of “implied authorisations by the Security Council” for them to use force,²²² and stricter compliance with the UN Charter would be required in the future. Notably, even a former Secretary-General of the United Nations supported this opinion of a majority of States within the international community, by having stated, at a press conference on 10 March 2003, in rather direct a manner: “If the US and others were to go outside the [Security] Council and take military action, it would not be in conformity with the Charter [of the United Nations].”²²³

4.2 Charter-Related Exceptions

The second group of exceptions to the prohibition of the use of force (cf. supra 2.1) is not to be found in the Charter of the United Nations explicitly but is still related to it and can be inferred, more or less credibly, from some of its programmatic and operative provisions. The UN General Assembly resolution 377 A (V) (“Uniting for Peace”) of 3 November 1950 (see infra 2.4.2.1) and the use of force in pursuance of peoples’ right to self-determination (see infra 2.4.2.2) are the principal examples.

4.2.1 “Uniting for Peace”

As the draft resolution “Uniting for Peace”²²⁴ was being discussed in the UN General Assembly, numerous arguments deriving from both positive international law and legal scholarship were suggested for and against it.²²⁵ It was noticeable already at the time that the Security Council’s procedure for the maintenance of international peace and security lacked perfection, and it was sought to remedy this flaw through the medium of the General Assembly (cf. supra 1.2.5.3). The first operative paragraph of the resolution read as follows:

The General Assembly […]

1. Resolves that if the Security Council, because of lack of unanimity of the permanent members, fails to exercise its primary responsibility for the maintenance of international peace and security in any case where there appears to be a threat to the peace, breach of the peace, or act of aggression, the General Assembly shall consider the matter immediately with a view to making appropriate recommendations to Members for collective measures, including in the case of a breach of the peace or act of aggression the use of armed force when necessary, to maintain or restore international peace and security. If not in session at the time, the General Assembly may meet in emergency special session within twenty-four hours of the request therefor. Such emergency special session shall be called if requested by the Security Council on the vote of any seven members, or by a majority of the Members of the United Nations.

Since 1956, ten emergency special sessions were convened under the resolution.²²⁶

The principal argument put forward against the resolution consisted in that it would constitute a violation of the UN Charter inasmuch as it would bequeath the General Assembly with a role, which is in fact the Security Council’s, and thereby ignore a fundamental working principle of the United Nations, i.e. the unanimity of all permanent members of the Security Council as a requisite condition for an effective maintenance of international peace and security.²²⁷ In turn, according to the resolution’s opponents, it was inconsistent with the UN Charter and constituted, technically, an illicit amendment thereof, contrary to Articles 108 and 109.²²⁸

However, although a strict division of tasks between the General Assembly and the Security Council was indeed intended by the Charter’s drafters, it was accomplished only to an extent.²²⁹ Under Article 24(1) of the Charter, the Security Council bears the “primary responsibility” for the maintenance of international peace and security. ²³⁰ Yet, as Juraj Andrassy noted, a literal reading of this expression suggests the existence of another—“subsidiary” or “supplementary”—responsibility, which, according to the resolution’s proponents, should have been conferred upon the General Assembly.²³¹ Under Article 10 of the Charter,²³² the General Assembly is authorized to discuss any questions or matters within the competence of the United Nations—and thus also matters of maintaining international peace and security, although they are under the “primary responsibility” of the Security Council.²³³ In Article 11(2),²³⁴ three types of possible reactions by the General Assembly with respect to such matters are distinguished: (1) a mere discussion of a question, (2) the adoption of a recommendation, and (3) the necessity of (enforcement) action.²³⁵ The General Assembly’s authority to discuss questions and matters within the scope of the UN Charter is not restricted. With respect to “action,” it is commonly acknowledged that it means an “enforcement action” or a “military action.”²³⁶ Since, in accordance with the second sentence of Article 11(2), the General Assembly may not itself take substantive decisions with respect to such questions and is obliged to refer them to the Security Council,²³⁷ paragraph 1 of resolution 377 (V) limits the Assembly’s competence to “making […] recommendations.” In the case of such a referral, the Security Council might not remain inactive (otherwise it would not act in accordance with the Purposes of the United Nations, cf. the Charter’s Article 1(1)), and would be duty-bound to take substantive decisions. It appears that the potential of the UN General Assembly resolution 377 (V) has not been sufficiently exploited, and its operative mechanism might help suppress at least some acts of aggression in the future. The capacity of the General Assembly as an international forum for exchange among nations and peoples with different political, economic and religious backgrounds, including in the area of maintaining international peace and security, is quite sizeable, and the Security Council—whose function consists in putting into action, promptly and effectively (cf. the first sentence of Article 24(1) of the UN Charter), the legitimate collective ambitions of all nations represented in the General Assembly—might not ignore the Assembly’s recommendations made under resolution 377 (V).

4.2.2 The Use of Force in Pursuance of Peoples’ Right to Self-Determination

The question whether national liberation movements might use force in pursuit of peoples’ right to self-determination²³⁸—and whether like-minded States might assist them in this pursuit²³⁹—has been on international lawyers’ agenda since after the Second World War (cf. supra 1.2 and infra 3.1.1–3.1.3). As the Charter of the United Nations (see specifically supra 1.2.5.1) whose Articles 73 and 74 dealt with the status of non-self-governing territories had entered into force, many of the former colonies started progressively claiming independence from their “mother countries,” including by military force. As Christine Gray recalls, this tendency started out by violent independence movements in Tunisia, Morocco and Algeria against France, in Malaya, Kenya and Cyprus against the UK, in Indonesia against The Netherlands, and in India against Portuguese authority in Goa.²⁴⁰ Especially the latter case caused a heated debate in the Security Council where some States maintained that the issue should be regarded as one of colonialism (for Portugal sought to preserve its authority in Goa), and another group of States argued that it was about India’s allegedly unlawful use of force breaching Article 2(4)²⁴¹ (cf. supra 2.1–2.2). As decolonization progressed, some ex-colonies and socialist States increasingly asserted the right for national liberation movements to use force—and for third States to support them—a claim that was resolutely resisted by Western States.²⁴² In the General Assembly (cf. supra 1.2.5.3), compromise solutions were found at the expense of ambiguity; Christine Gray identified at least three relevant examples. The key document on decolonization—the 1960 Declaration on the Granting of Independence to Colonial Countries and Peoples²⁴³—made no direct reference to the use of force but some of the subsequent resolutions on the subject did use expressions, which could be interpreted as endorsing the use of force in certain circumstances.²⁴⁴ Thus, resolution A/RES/2105 (XX) “recognise[d] the legitimacy of the struggle by the peoples under colonial rule to exercise their right to self-determination and independence and invite[d] all states to provide material and moral assistance to the national liberation movements in colonial territories” (emphasis added).²⁴⁵ Christine Gray notes that the meaning of “struggle”—whether it meant in this specific context “armed struggle” or “peaceful struggle”—remained unclear²⁴⁶; it appears to this author that the word’s usual literary meaning does imply the permissibility of a use of force. In a similar way, the 1970 Friendly Relations Declaration did not plainly allow for the use of force by national liberation movements but it called upon States

[t]o refrain from any forcible action which deprives peoples […] of their right to self-determination and freedom and independence. In their actions against, and resistance to, such forcible action in pursuit of the exercise of the right to self-determination, such peoples are entitled to seek and to receive support in accordance with the purposes and principles of the Charter.²⁴⁷

A comparable approach was used in Article 7 of the General Assembly resolution 3314 (XXIX) (cf. supra 2.3):

Nothing in this Definition […] could in any way prejudice the right to self-determination, freedom and independence, as derived from the Charter, of peoples forcibly deprived of that right and referred to in the Declaration on Principles of International Law concerning Friendly Relations and Co-operation among States in accordance with the Charter of the United Nations, particularly peoples under colonial and racist regimes or other forms of alien domination; nor the right of these peoples to struggle to that end and to seek and receive support, in accordance with the principles of the Charter and in conformity with the abovementioned Declaration.²⁴⁸

As the issue of the use of force in the context of self-determination currently remains pertinent—principally, if not exclusively—only in the context of Palestine²⁴⁹ and the continued occupation of the West Bank and Gaza by Israel (cf. supra 2.1.3.2),²⁵⁰ it may for the most part be regarded as one of the past. Ethnic groups’ claims to secession from existing States based on the right to self-determination are typically not supported by States.²⁵¹ In the few remaining contexts where self-determination remains on the agenda, the United Nations must take all necessary measures to ensure, to the maximum extent possible, its progressive and peaceful implementation, with due regard to the interests of and in association with all parties involved, for the risks inherent in the lasting inter-ethnic and interreligious conflict in the area—if not managed aptly—may result in dramatic effects to the Middle East and the world at large.

4.3 Extra-Charter Exceptions

The extra-Charter exceptions to the prohibition of the use of force are the most problematic in the sense that they have no express or implicit foundations in the Charter of the United Nations and derive, in the quality of emerging norms of customary international law, from extra-Charter sources of international law. As these rules are not yet codified in written sources, their content remains vague, and the quality of international recognition is not undisputed. In this sense, they may be termed “purported”—or, in the best of cases, “emerging”—exceptions to the prohibition of the use of force (cf. supra 2.1). The three most notable examples we will focus upon are the protection of nationals abroad (see infra 2.4.3.1), the so-called “humanitarian intervention” (see infra 2.4.3.2), and the “pro-democratic intervention” (see infra 2.4.3.3).

4.3.1 Forcible Protection of Nationals Abroad

The political and scholarly discussion on the legitimacy of the so-called “forcible protection of nationals abroad” has been ongoing for decades now. The substantive basis for this important debate consisted in military interventions carried out by a few States in other States, without the Security Council authorizations, for the purpose of rescuing and/or evacuating their nationals who were menaced by a collapse of law and order or by other life-threatening dangers in the respective target States.²⁵² As Christine Gray notes, there is currently no unity of opinion among policy-makers as to the legality of such military actions: throughout numerous debates within the Security Council and the General Assembly,²⁵³ many of these claims were regarded as pretexts to intervene in States’ domestic affairs, in violation of a respective Principle of the United Nations,²⁵⁴ and as a modern type of the nineteenth century “gunboat diplomacy.”²⁵⁵ Consultations on the issue of diplomatic protection, which were held in the General Assembly in 2000, contributed to this important debate.²⁵⁶ It appears that customary international law on the “forcible protection of nationals abroad,” as it currently stands, does not spell out either the range of exceptional circumstances where States might have recourse to military force to protect or rescue their nationals abroad or the extent of such force, which could be used to this end.

Among scholars, the supporters and antagonists of the concept have fashioned more than a few mutually exclusive views based, chiefly, on the Charter of the United Nations and its relevant travaux préparatoires.²⁵⁷ Both opposing groups included outstanding authorities in international law, and many scholars have at times claimed to represent the prevalent views, but it seems very difficult to establish which group is, as a matter of fact, more representative²⁵⁸; it is probably more accurate to say that, to date, the legal scholarship has been largely incapable of bringing contradictory State practices to a common denominator.

At times, the military operations under discussion are regarded as a sub-type of “humanitarian intervention” (see infra 2.4.3.2), as both types of operations (1) take place outside the territory of the intervening State, (2) involve the use of inter-State military force in the sense of Article 2(4) of the Charter (cf. supra 2.1), and (3) aim at preventing the infliction of physical harm on identifiable persons or groups in the territory of the target State.²⁵⁹ Still, there exists common agreement that, from the point of view of international law, the two types of operations must be kept distinct.²⁶⁰ The principal reason for that distinction is in those operations’ different ratione personae fields of application: whereas the purpose of “humanitarian intervention” is to protect the target State’s population against massive and/or grave violations of human rights, military operations for the protection of nationals seek to defend the intervening States’ own nationals whose lives or physical integrity are under an imminent threat in the to-be-attacked State.

As a rule, States and publicists justify the “forcible protection of nationals” by a combination of three cumulative conditions: (1) there has to exist an impending threat of physical injury being caused to a State’s nationals; (2) the territorial sovereign must be unwilling or unable to protect them, and (3) the military action of the intervening State may not extend beyond the purpose of protecting its nationals against the identified impending threats.²⁶¹ It is not doubted that States’ right to such interventions was undisputed before 1945.²⁶² Likewise, it is agreed that they are fully consistent with the Charter of the United Nations where the host State grants its consent to an intervention. On the other hand, whether States’ military operations aimed at protecting their nationals by force where no such sovereign consent is granted, or where its authority is dubious—for example, where there is a high intensity non-international armed conflict ongoing within the to-be-attacked State—are compatible with relevant international law (cf. supra 2.1) is one of the principal issues of present-day jus ad bellum.²⁶³

Scholars who favor the “forcible protection of nationals” doctrine give a number of reasons.²⁶⁴ One group of publicists suggests, quite plausibly, that such military operations do not breach the prohibition of the use of force contained in the Charter’s Article 2(4), because they do not affect the “territorial integrity or political independence” of a State; their only aim is to rescue foreign nationals from an imminent threat, which the host State is unable or unwilling to remove.²⁶⁵ According to another mainstream approach, military operations aimed at providing protection to a State’s nationals abroad represent a form of self-defence under Article 51 of the Charter of the United Nations ²⁶⁶ (cf. supra 2.4.1.1). A two-level argument is often offered to substantiate this claim. First, it is asserted that the Charter recognized the inherent right of States to self-defence (cf. supra 2.4.1.1.2), which implies this right’s rather broad interpretation in the context of the relevant pre-existing customary international law, which had encompassed, inter alia, the right of each State to protect its nationals abroad. Second, it is suggested that a State’s nationals who are temporarily abroad do still constitute a part of that State’s population and thus embody its basic attribute²⁶⁷; hence, a deliberate attack against that State’s nationals abroad may be taken for an attack against the State itself, and the State might, on this basis, exercise its right to self-defence on the basis of Article 51. Occasionally, some other justifications have been offered but they did not become as common as these two; they included references to the existence of a “state of necessity”²⁶⁸ or to “humanitarian considerations” and fundamental human rights.²⁶⁹ Another group of publicists have maintained, probably most accurately, that the right of State to protect its national abroad should be considered as a novel, essentially customary in nature and self-sufficient exception to Article 2(4), as it cannot be easily placed into the current framework of international law.²⁷⁰ This author tends to agree to the permissibility of the mechanism under discussion, on the condition that it be resorted to as a matter of exceptional legitimacy where a host State is manifestly unable or unwilling to remove the threat, especially where the level of violence against individuals requiring protection reaches that of a widespread or systematic attack in the sense of Article 7(1) of the Rome Statute. Of course, it is understood that a State so intervening in another State must immediately withdraw, together with its rescued nationals, once the operation is over, and must be prepared to subsequently justify its good intention in a court of law.

4.3.2 “Humanitarian Intervention”

Likewise, the legal regulation of the so-called “humanitarian intervention” is among the most complex issues of modern jus ad bellum.²⁷¹ Sean Murphy defined “humanitarian intervention” as “the threat or use of force by a State, group of States, or international organization primarily for the purpose of protecting the nationals of the target state from widespread deprivations of internationally recognized human rights.”²⁷² The key issue here is exceptionally difficult: should States be permitted as a matter of international law to intervene militarily, without a Security Council authorization, in other States, in order to stop genocide or other atrocities of a comparable magnitude?²⁷³

During the past decade, the issue became particularly important in connection with international coalitions’ interventions in Kosovo (1999)²⁷⁴ and Iraq (2003) as well as with the community of States’ failure to do so in the Sudan.²⁷⁵ The principal apprehension related to the legitimacy of “humanitarian intervention” is that, if it is once legalized, States would exploit it as a pretext for waging wars to attain their selfish national interests.²⁷⁶ This policy problem was well known since the time of Grotius and the medieval European classics of international law that followed him (see supra 1.1.2.4). The doctrine of “humanitarian intervention” had been quite influential at the beginning of the twentieth century,²⁷⁷ before the League of Nations erected initial legal barriers to the inter-State use of force after the end of the First World War (see supra 1.1.6.1–1.1.6.2). After the entry into force of the Charter of the United Nations’ (cf. supra 1.2.5.1), the center of gravity in the international political²⁷⁸ and scholarly²⁷⁹ debate determinedly shifted towards opposing “humanitarian intervention.” Notably, even States that have themselves been involved in “humanitarian interventions” without Security Council authorizations, tended not to justify their conduct in terms of a legal right to practise such interventions, and explained it as ad hoc solutions.²⁸⁰

Although some publicists have suggested otherwise,²⁸¹ it is widely agreed that international law forbids States to use force unilaterally even for the purpose of rescuing victims of humanitarian catastrophes.²⁸² The chief treaty regulating the use of force, the Charter of the United Nations does not name “humanitarian interventions” among lawful exceptions to Article 2(4) (cf. supra 2.4.1–2.4.2), and relevant General Assembly resolutions confirm this overarching rule²⁸³ (cf. supra 1.2.5.3). It was also confirmed by the International Court of Justice²⁸⁴ and recognized in leading treatises that “humanitarian intervention” was prohibited under both the relevant treaty law and customary international law, some inconsistent State practices over the past decade or so notwithstanding.²⁸⁵

In light of the issue’s undoubted importance, one may assume, though, that the legal regulation of humanitarian intervention might develop, to some extent, in a foreseeable future. Following ECOWAS interventions in Liberia (1990) and Sierra Leone (1997) and NATO’s intervention in Kosovo (1999), some authors appeared to suggest that new rules allowing for an exception to the prohibition of the use of force under Article 2(4) of the Charter might be emerging.²⁸⁶ Some time ago, even a codification of the law of “humanitarian intervention” was suggested in the doctrine.²⁸⁷ It remains to be seen whether and to which extent States—whose majority expressed themselves against the legitimisation of humanitarian intervention some time ago (cf. supra note 279)—might allow their practices and opinio juris to take an alternative direction.

4.3.3 “Pro-democratic Intervention”

Whereas the US-led coalition’s intervention in Iraq in March 2003 divided opinions within the international community,²⁸⁸ the declared aim of introducing democracy in that country after the establishment of a military occupation regime was not practically contested. The change of Iraq’s political regime from dictatorial to democratic was an official political end of Operation Iraqi Freedom,²⁸⁹ in line with the dual ambition of President George W. Bush’s administration, on the one hand, to remove threats emanating from “rogue” States and, on the other hand, to proliferate democracy—the Middle East and, more generally, the Muslim world being a special focus of this aspect of the United States’ foreign policy.²⁹⁰

It seems that this ambition, however inconsistent with the pre-existing international law in force it might have been, did manage to influence the practice of the Security Council to a sizeable extent, at least for the duration of President Bush’s terms of office. As W. H. Taft IV and T. F. Buchwald argued, Operation Iraqi Freedom had found its legal basis in a specific reading of the Security Council resolutions 678 (1991), 687 (1991), and 1441 (2002), whereby the purported “material breach” of Iraq’s disarmament obligations under resolution 687 (1991) recovered the right to use armed force provided under resolution 678 (1991).²⁹¹ For our purpose, the question is to which extent the Security Council resolutions 1483 (2003), 1511 (2003), and 1546 (2004)—which were adopted in the aftermath of the intervention with a view to giving legal effect to the reality of a forcible regime change—might be regarded as reflections of the Security Council’s legitimate political authority in accordance with the Charter of the United Nations.

It may appear that Iraq’s “forced democratization” is not coherent with current international law: in accordance with Article 43 of the Regulations annexed to the 1907 Hague Convention (IV) with respect to the Laws and Customs of War on Land, an intervening State, which establishes a military occupation regime, is obliged to respect “unless absolutely prevented, the laws in force in the [occupied] country.” Article 43 embodies customary international law,²⁹² and the forced democratization of occupied territories must consequently be disallowed. Yet, this conclusion is somewhat incomplete in view of Articles 24(1) and 103 of the Charter of the United Nations: if the UN Members’ obligations under the Charter prevail over those under other international treaties, including the 1907 Hague Convention (IV), and the Members agree that, in carrying out its duties for the purpose of maintaining international peace and security, the Security Council acts on their behalf, one may conclude that resolutions of the Security Council may, in certain cases, deviate from written international law, even if relevant provisions also amount to customary law (as the 1907 Hague Regulations do). As a matter of practice, there is little use in some Council members’ ex post facto critique of the US-led coalition’s intervention in and occupation of Iraq and the subsequent regime change, if they themselves allowed for the adoption of relevant Security Council resolutions, by not having vetoed them. To conclude on this issue, the Security Council’s indecisive behavior with respect to developments in Iraq—and, later, also in Libya—established critical precedents whose future implications remain to be seen.²⁹³