1. Introduction
While the position that international organizations occupy in the international legal system remains elusive, it has been progressively accepted that customary international law – or at least some of it – applies to them.Footnote 1 Nothing exemplifies this trend more than the projects that the International Law Commission carried out to codify and progressively develop the law of treaties and the law of responsibility of international organizations. The essential premise behind the 1986 Vienna Convention on the Law of Treaties between States and International Organizations or between International Organizations (VCLT 1986) and the 2011 Articles on the Responsibility of International Organizations for Internationally Wrongful Acts (ARIO) is that most of the customary rules on treaties and responsibility that govern the relations between states can be extended to international organizations.
If one accepts that international organizations are subject to the rules of general international law,Footnote 2 one of the fundamental questions that arise concerns the scope of application of those rules. It should be uncontroversial that general international law applies when international organizations relate to the outside world, that is, when they maintain relations with third parties on the international plane that are not – nor could be – governed by constituent instruments and other internal rules. Those ‘external relations’ correspond, however, to just a small fraction of the functions that international organizations are set up to perform. The bulk of their activities takes place on the institutional plane, where internal rules provide for myriad powers, rights, and duties, normally involving action directed at member states. What is, then, the role, if any, that general international law can play in the relations between international organizations and their members?
The assumption underlying the International Law Commission’s (ILC) codification efforts is that the general law of treaties and the general the law of responsibility apply not only when international organizations relate to the outside world but also to interactions between organizations and members. That assumption is left implicit in VCLT 1986 but is fleshed out in the ARIO, with Article 10(2) providing that the existence of a breach of an international obligation triggering the responsibility of an organization ‘includes the breach of any international obligation that may arise … towards its members under the rules of the organization’.Footnote 3 My aim in this article is to question and further qualify that assumption. I investigate the applicability of general international law between international organizations and their members by distinguishing between two categories of relations.Footnote 4 The first comprises relations that take place on the international plane notwithstanding that they involve entities which remain bound by the internal rules of the organization. The second concerns relations situated on the institutional plane, where rights, obligations, and capacities are governed by constituent instruments and other internal rules. I argue that general international law applies by default to relations belonging to the first category (Section 2.1), only being displaced when the internal law of an organization contains applicable lex specialis (Section 2.2). General international law cannot, however, claim a similar role at the level of internal institutional relations (Section 3.1). The question there becomes one concerning the dialogue between relatively autonomous international legal orders similar to that posed when one addresses the relations between international law and domestic legal systems. That means that it is the internal law of each organization that ultimately defines the terms on which rules of international law are allowed into the institutional plane (Section 3.2). At the same time, I advance a normative argument for a ‘monistic presumption’ for the application of general international law in cases where the rules of the organization are silent (Section 3.2.1), and consider some of the limits of this presumption (Section 3.2.2). The article concludes with an illustration of how the analytical framework that it sketches can be applied (Section 4).
Because it delves into questions of applicable law, the main contribution that this article makes is methodological in character. Its ambition is to help international lawyers dealing with complex disputes opposing international organizations and their members structure the legal analysis. In any given case, should general international law be the starting point for the analysis, with the rules of the organization only playing a role to the extent that they contain applicable lex specialis? Or should one rather start with the rules of the organization, with general international law filling the occasional gap only to the extent allowed by those rules? In either case, what is the analytical framework that explains the interplay between general international law and the rules of the organization?
It is often the case that an act performed by an organization or one of its members gives rise both to questions of international law (their rights and obligations as international legal subjects on the international plane) and to questions of institutional law (their rights and obligations under the rules of the organization). General international law may have a role to play in tackling both categories of questions but it does so on different grounds and to varying extents. Much confusion can result when the international and institutional planes are unreflectively conflated,Footnote 5 ranging from sloppy assumptions that general international law is always immediately applicable to objectionable strategies to limit its application. In addressing the possible facets of any given dispute, international lawyers must be able to identify and follow the steps of the legal analysis that pertains to the category to which the aspect being considered belongs. That is why the methodological inquiry carried out in this article is apposite.
2. Relations on the international plane
2.1 General international law as the applicable law
Because international organizations and their members act in tandem on the international plane, not all of the relations between them fall under the institutional framework laid down by constituent instruments and other internal rules. Consider, for example, transactions taking the form of a bilateral treaty. When an organization and a member express their consent to be bound by a headquarters agreement, they do not do so in their ‘institutional capacity’ but rather as autonomous legal persons operating on the international plane. The International Court of Justice took this view in its advisory opinion on Interpretation of the Agreement of 25 March 1951 between the WHO and Egypt. Tasked with identifying the rules and principles governing the World Health Organization’s transfer of its regional office from Egypt, the Court described the rights and obligations arising from the headquarters agreement concluded between them as a ‘contractual legal régime’ reached by the parties by ‘mutual understandings’.Footnote 6 Likewise, the Court noted in its seminal opinion on Reparation for Injuries Suffered in the Service of the United Nations that it would be ‘difficult to see’ how the 1946 Convention on the Privileges and Immunities of the United Nations ‘could operate except upon the international plane and as between parties possessing international personality’.Footnote 7 Neither the 1951 Agreement nor the 1946 Convention derive their validity from the internal law of the WHO or the UN. Instead, both are subject to the general law of treaties.
The same idea can be traced back to the ILC’s work on the law of treaties involving international organizations. While the Commission avoided taking a clear position on the project’s scope of application, the term ‘treaty’ was broadly defined as ‘an international agreement governed by international law and concluded in written form between one or more states and one or more international organizations or between international organizations’.Footnote 8 In the commentary to the draft articles (later sent for adoption at the 1986 Vienna Conference on the Law of Treaties), the Commission stated that agreements between organizations and members were governed by international law unless a contrary intention was expressed:
If an agreement is concluded by organizations with recognized capacity to enter into agreements under international law and if it is not by virtue of its purpose and terms of implementation placed under a specific legal system (that of a given state or organization), it may be assumed that the parties to the agreement intended it to be governed by general international law.Footnote 9
It is true, as Special Rapporteur Paul Reuter pointed out, that the ‘internal law’ of an international organization could constitute ‘a highly developed legal system of its own, to which … a conventional act should be subject in its entirety’. In such cases, the relations between the organization and members would be ‘removed in their entirety from the sphere of general international law’ and placed under that ‘highly developed legal system’.Footnote 10 But unless this is provided for or otherwise inferred, the ultimate source of the validity of treaties between members and international organizations remains the customary principle pacta sunt servanda.
The same applies to responsibility for breaches of international obligations owed between organizations and members. Whenever international organizations and their members can be viewed as legally autonomous entities operating on the international plane, their relations will be governed by general international law.
2.2 The rules of the organization as lex specialis
That general international law covers relations external to the institutional framework of an international organization does not mean, however, that it is always applicable between organization and members to the same degree that it would be in relations opposing the organization and a third party. Under the principle pacta tertiis nec nocent nec prosunt,Footnote 11 the rules of organization are res inter alios acta between the organization and a third party and cannot have the effect of displacing the general rules of public international law applying between them. The commentary to the ARIO accurately observes that the internal law of an organization ‘cannot per se affect the obligations that arise as a consequence of an internationally wrongful act’ vis-à-vis a state which is not a member of that organization.Footnote 12 In contrast, between an organization and its members, constituent instruments and other internal rules may be part of the applicable law as lex specialis. To the extent that the rules of the organization constitute a source of rights and obligations both for the organization and its members, they may affect the general law applying to their relations even on the international plane.
But can the rules of the organization be indeed characterized as lex specialis applicable on the international plane? In an insightful study, Christiane Ahlborn suggested that because an international organization ‘is not a contracting party to its constituent instruments under international law’, restrictions imposed by those instruments do not apply to relations taking place outside the institutional framework.Footnote 13 It is doubtful, however, that the notion of lex specialis has to be construed this narrowly. Lex specialis is a ‘technique of interpretation and conflict resolution’ according to which ‘wherever two or more norms deal with the same subject matter, priority should be given to the norm that is more specific’.Footnote 14 Applying it to relations between an organization and its members means recognizing that, even if the character of the rules of the organization is ‘institutional’ (or ‘constitutional’) as opposed to ‘contractual’, the rules of the organization remain a source of rights and obligations for the entities concerned. There is no reason why such rules should not displace the general law in the same way as any other special rule: as the ILC pointed out in its Conclusions on the Fragmentation of International Law, ‘[t]he source of the norm (whether treaty, custom or general principle of law) is not decisive for the determination of the more specific standard’.Footnote 15
Consider, for example, the rule in Article 103 of the UN Charter, which prescribes that ‘[i]n the event of a conflict between the obligations of the Members of the United Nations under the present Charter and their obligations under any other international agreement, their obligations under the present Charter shall prevail’. If the UN Security Council (UNSC) were to adopt a resolution under Chapter VII of the Charter that conflicts with the provisions of a headquarters agreement between the UN and a member state, there would be little sense in denying that that resolution, in the light of Article 103, would constitute lex specialis displacing the rule that applies to the parties on the international plane, even if the grounds on which the member and the UN are bound by the Charter differ. The relations between organization and members typically occur under the ‘vertical’ institutional framework established by the constituent instrument; but the fact that they can also interact on the ‘horizontal’ international plane creates the occasion for the two legal orders to intersect. That invites further reflection on the forms that lex specialis may take in international law, without losing sight of the rationale and the purpose of the doctrine, namely to provide a structural norm for solving conflicts between rules applying to the same situation.
The proposition that constituent instruments and other internal rules may constitute lex specialis applicable in the relations between organizations and members is expressed in a few provisions of the ARIO. First, Article 32 prescribes that the responsible organization ‘may not rely on its rules as justification for failure to comply with its obligations’ of cessation of or reparation for an internationally wrongful act that it has committed, but then emphasizes that the general rule is ‘without prejudice to the applicability of the rules of an international organization to the relations between the organization and its [members]’. As a result, Article 32 is entitled ‘relevance of the rules of the organization’, in contrast to its counterpart in the Articles on the Responsibility of States for Internationally Wrongful Acts (ARS), the title of which is ‘irrelevance of internal law’. Secondly, Articles 22 and 52 prescribe that countermeasures may be taken between organizations and members, in reaction to breaches of obligations other than those arising under the rules of the organization, only insofar as ‘the countermeasures are not inconsistent with the rules of the organization’. Thirdly, the general clause on lex specialis contained in Article 64 clarifies that special rules that may affect the conditions for the existence of an internationally wrongful act or the content or implementation of the ensuing responsibility ‘may be contained in the rules of the organization applicable to the relations between an international organization and its members’.
Similar provisions are nowhere to be found in the 1986 Vienna Convention. The most glaring omission is in Article 27, with the rule whereby ‘[a]n international organization party to a treaty may not invoke the rules of the organization as justification for its failure to perform the treaty’ not making any special allowances – unlike Article 32 ARIO – for treaties between international organizations and members. Article 5, common to the 1969 Vienna Convention on the Law of Treaties (VCLT 1969) and VCLT 1986, is the only provision to make a modest attempt at regulating the question of lex specialis. It prescribes that the application of the two Conventions to ‘the constituent instrument of an international organization’ and to ‘any treaty adopted within an international organization’ is ‘without prejudice to any relevant rules of the organization’. Article 5 provides, in the words of a leading commentator, a ‘broad and variable exception’ that may allow the law to develop ‘along lines peculiar and appropriate to those instruments and their function in the international community’.Footnote 16 But because the scope of Article 5 is narrow, it can hardly be construed as a general lex specialis clause applying to treaties concluded between organization and members, unless the notion of ‘treaty adopted within an international organization’ is stretched far beyond its ordinary meaning.Footnote 17
The reason why the ILC did not inquire into the effect of constituent instruments and other internal rules on treaties concluded an organization and its members appears to be twofold. First, the Commission treated the matter as one going beyond the purview of the law of treaties. The commentary states that the rule now contained in Article 27 VCLT 1986 pertains ‘more to the regime of international responsibility than to the law of treaties’ and as such constitutes ‘an incomplete reference to problems’ which not even the 1969 Vienna Convention purported to tackle.Footnote 18 Second, the ILC made a conscious effort not to delve into the boundaries between general international law and the internal law of each organization. As Special Rapporteur Reuter noted in the debate, if an organization ‘concluded a treaty with one of its member states and at a later stage made changes in its rules that were binding on all its member states, its constitution might be in conflict with the treaty and with a treaty right or a right derived from a treaty’; to his mind, the Commission ‘was not required to resolve problems of that type, since they constituted a special case of conflict, which was covered by the rules of each organization’.Footnote 19
Adding even more ambiguity to an already convoluted approach is a statement that Special Rapporteur Reuter made when the Commission debated the rule now found in Article 46 VCLT 1986, concerning ‘provisions of internal law of a state and rules of an international organization regarding competence to conclude treaties’. Reuter suggested that ‘in the case of a treaty between an organization and one or more of its members, the question of invalidity was not subject to rules of general international law’,Footnote 20 for ‘[c]ases of that kind must be settled by the special law and practice of the organization’.Footnote 21 Yet, the commentary that the Commission eventually adopted arrives to the opposite conclusion. It goes as far as pointing out that members ‘must be aware of the rules regarding the conclusion of treaties’ as they participate in the decision-making of the organization and thus ‘assume a share of the responsibility for the conclusion of irregular treaties’.Footnote 22 The rule in Article 46 is thus affirmed to apply between organizations and members.
That the ILC embraced the proposition that the rules of the organization are lex specialis for organizations and their members in the ARIO, but dodged it in the project on the law of treaties, suggests that there is some uncertainty as to the precise ways in which rights and obligations assumed on the international plane may affect rights and obligations accruing on the institutional plane. In some cases, constituent instruments will seek to clarify the issue, as with Article 103 of the UN Charter as discussed above. In others, no automatic priority between rules arising from one category or the other should be assumed in cases of conflict. Conflict should be treated as a matter for ‘contextual appreciation’ taking into account other norms of interpretation or conflict resolution, in particular the overarching goal envisaged by the ‘principle of harmonization’, according to which ‘when several norms bear on a single issue they should, to the extent possible, be interpreted so as to give rise to a single set of compatible obligations’.Footnote 23
2.3 Mutual obligations of co-operation and good faith
While the rules of the organization are the source of lex specialis most likely to affect the relations between international organizations and members taking place on the international plane, attention must also be paid to special (customary) rules in the law of international organizations that can emerge as practice and precedent evolve.Footnote 24 A potentially relevant special rule was identified by the ICJ in Interpretation of the Agreement. Having described the arrangements between the WHO and Egypt leading to the establishment of a regional office of the WHO in Alexandria as a ‘contractual legal régime’, the Court observed that ‘[t]he very fact of Egypt’s membership of the Organization entails certain mutual obligations of co-operation and good faith incumbent upon Egypt and upon the Organization’.Footnote 25 Judge Ago further noted, in this connection, that the ‘legal relations between an international organization and the host state constitute a special régime’.Footnote 26
The ILC relied on the notion of mutual obligations and good faith when it considered rules on countermeasures applicable to relations taking place outside the institutional framework. Articles 22(2) and 52(1) ARIO first of all prescribe that countermeasures must not be ‘inconsistent with the rules of the organization’. The two provisions go beyond that, however, by specifying that countermeasures may only be taken if ‘no appropriate means are available for otherwise inducing compliance with the obligations of the responsible international organization concerning cessation of the breach and reparation’. This additional requirement, which finds no counterpart in the law of state responsibility, is meant to give expression to the ‘principle of cooperation underlying the relations between an international organization and its members’.Footnote 27 Such a ‘principle of cooperation’ could potentially also justify the rule found in paragraph 4 of Article 51 ARIO, which provides that countermeasures are to be taken ‘in such a way as to limit their effects on the exercise by the responsible international organization of its functions’.Footnote 28
The proposition that transactions between an organization and members on the international plane may be affected in various ways by normative considerations arising from the ‘organic link’Footnote 29 that brings them together on the institutional plane is one worth considering. But the extent to which insisting in a special category of ‘mutual cooperation and good faith’ for international organizations and members is helpful in addressing concrete problems is up for debate. Does it add much to the principle of good faith under general international law, which, as the ICJ stated in Nuclear Tests, is ‘[o]ne of the basic principles governing the creation and performance of legal obligations’, for ‘[t]rust and confidence are inherent in international co-operation’?Footnote 30 Good faith is, after all, an essentially contextual obligation, the specific requirements of which can only be formulated in the light of the particular circumstances of any given relationship.
When international organizations and members interact on the international plane, the degree of trust and confidence that characterizes their relationship means good faith can be particular demanding. But it is telling that in Interpretation of the Agreement, the mutual obligations of co-operation and good faith merely provided a starting point for the Court’s reasoning.Footnote 31 To determine the ‘legal principles and rules applicable to the question under what conditions and in accordance with that modalities a transfer of the [WHO’s] Regional Office from Egypt [could] be effected’, the Court relied on a number of comparable host agreements and on the rule found in Article 56(2) of the two Vienna Conventions on the Law of Treaties, from which it extrapolated obligations of consultation and reasonable notice.Footnote 32 It was only able to spell out what precisely mutual co-operation and good faith entailed for the WHO and Egypt in the circumstances by drawing from relevant international practice and general international law itself. Thus, one should be cautious not to overplay the role that mutual obligations of co-operation and good faith can play in the abstract. They are unlikely to affect, to a significant extent, the proposition that general international law applies to the relations between organizations and members on the international plane.
3. Relations on the institutional plane
3.1 Distinguishing between international legal orders
In the codification and progressive development of the law of treaties, the ILC maintained an ambiguous position on the scope of application of its project, in particular as regards the relations between organizations and members. The Commission’s ambition for the responsibility project was expressed in much clearer terms. The Working Group established to initiate work on responsibility acknowledged that ‘the great variety of relations existing between international organizations and their member states and the applicability to this issue of many special rules’ would ‘probably limit the significance of general rules in this respect’.Footnote 33 It concluded, however, that questions of responsibility arising from those relations should not be excluded from the purview of the project.Footnote 34 As a consequence, the definition of ‘breach of an international obligation’ adopted in Article 10 ARIO includes breaches of obligations ‘that may arise for an international organization towards its members under the rules of the organization’. The ARIO purport to cover not only responsibility arising from the breach of obligations on the international plane but also questions of responsibility arising on the institutional plane.
But is this a claim that the ARIO can plausibly make? The ILC adopted Article 10(2) against the backdrop of a heated doctrinal debate, which it did not handle well. This debate concerns the character of the ‘rules of the organization’: whether they are part of public international law or rather constitute ‘internal law’ that is comparable to the domestic law of states. The Commission conceded that this question was ‘far from theoretical’ for the purposes of the project, as it affected ‘the applicability of the principles of international law with regard to responsibility for breaches of certain obligations arising from the rules of the organization’.Footnote 35 But it decided not to express ‘a clear-cut view’.Footnote 36 Instead, the commentary suggests, cryptically, that ‘to the extent that an obligation arising from the rules of the organization has to be regarded as an obligation under international law, the principles expressed in the present article apply’.Footnote 37 It then points out that ‘[b]reaches of obligations under the rules of the organization are not always breaches of obligations under international law’.Footnote 38 The debates suggest that this distinction between ‘international’ and ‘institutional’ obligations would be one between obligations arising from ties of membership (for example, those that arise for members of the UN when the UNSC adopts a resolution under Chapter VII of the Charter) and obligations concerning the functioning of the organs of the organization (for example, the law applicable to international civil servants).Footnote 39 The view that ties of membership give rise to international obligations extrapolates from the proposition that treaties (here, constituent instruments) are a source of obligations for states on the international plane.
This is, however, a slippery slope. The rules of the organization are no doubt part of international law if by this it is meant that, unlike the constitution of a state, they derive their validity from international law.Footnote 40 But as the International Court observed in Nuclear Weapons (WHO Request), while ‘[f]rom a formal standpoint, the constituent instruments of international organizations are multilateral treaties’, they are ‘treaties of a particular type’, their object being ‘to create new subjects of law endowed with a certain autonomy, to which the parties entrust the task of realizing common goals’.Footnote 41 The dual character of these treaties, which are ‘conventional and at the same time institutional’,Footnote 42 distinguish them from other multilateral treaties. While the fact that international organizations are established by treaty means that their internal law is international in origin, the treaty performs a constitutional role by laying down a discrete legal system governing the relations between international organizations and their members on the institutional plane.Footnote 43 In his individual opinion in Appeal Relating to the Jurisdiction of the ICAO Council, Judge de Castro expressed this idea as follows:
each [international] organization has a constitution which provides it with a general rule to which all its members are subject … It is the fact that the organization is a legal person which prevents the legal relationships between its members being considered as governed by a series of independent bilateral treaties … Members of the organization are linked together by the constitution, and their relationships are governed by the constitution. Such relationships are those resulting from the status of member of the organization, and not the status of a party to bilateral treaties. This is of the very essence of organizations; it is required by the common interest, and is a necessity for their functioning and effectiveness.Footnote 44
The relative autonomy of the internal law of personified entities is an inherent attribute of their legal personality. As Hans Kelsen has explained, the constituent rules of a ‘juristic person’ always constitute a ‘partial legal order’ which is separate from – albeit in a relationship with – the ‘total legal order’ under which that juridical person is established.Footnote 45 The rules of each international organization constitute ‘partial legal orders’ of international law, so that, as Ahlborn puts it, ‘they operate as a constitution that guarantees the autonomy of an international organization and that of its internal legal order’.Footnote 46 The relations taking place on the institutional plane are thus characterized by the ‘organic link’ existing between the organization and its members, a link whose logic is comparable to that of regimes of constitutional and administrative law within the state.Footnote 47 Lazar Facsaneanu helpfully distinguishes between ‘le droit international’, applying between international legal subjects on the international plane, and ‘le droit interne des sujets de droit international’, comprising the related categories of ‘droit interne étatique ou national’ – municipal law – and ‘droit interne des entités non-étatiques’ – the internal law of international organizations.Footnote 48 These two categories occupy ‘des positions symétriques’,Footnote 49 in that they govern the internal affairs of the international legal subject with relative autonomy from international law.
From this it follows that general international law cannot claim a direct or immediate role in regulating the relations between an international organization and its members on the institutional plane. Rather, the key to understanding its role lies in identifying the terms on which relations between legal orders of an international origin occur.Footnote 50
3.2 The terms of the relations between international legal orders
From the perspective of the international legal system, the terms on which international law relates to domestic law take the form of two broad and complementary principles. First, domestic rules cannot be invoked as a justification not to comply with international obligations.Footnote 51 Second, states are free to choose the means by which they implement their obligations so long as the action that they take results in compliance with the international rule.Footnote 52 Thus, international law seeks neither to determine the content of domestic lawFootnote 53 nor to affect its validity.Footnote 54 On the international plane, conflict between international law and domestic law is treated as an instance of state responsibility, giving rise to obligations of cessation and/or reparation for the state acting wrongfully. That means that states may adopt whatever constitutional arrangements they wish to regulate the incorporation of international rules into domestic law: the choice between ‘monism’ and ‘dualism’ is left to domestic law.Footnote 55
By comparison, the relations between legal orders of an international origin are under-conceptualized and the principles that govern them are less clear. The terms of those relations must depend, in the first instance, on what general international law – the ‘total legal order’ under which the different ‘partial legal orders’ are constituted – has to say. In contrast to ‘rules of incorporation’ found in many domestic systems, which impose several requirements for the establishment and functioning of companies and other juridical persons, there are very few limits to the freedom that states enjoy in setting up international organizations to fulfil tasks of international co-operation. Most of international law is, after all, jus dispositivum from which states are free to contract out in their mutual relations.Footnote 56 As a result, general international law leaves it to the internal law of each international organization to determine how the ‘partial legal order’ will relate to the ‘total legal order’. The rules of general international law will be applicable between an organization and its members on the institutional plane to the extent that the rules of the organization so allow. There is, thus, a marked similarity between the terms of the relations between international legal orders and those of the relations between international law and domestic legal systems.
That said, as the ‘total legal order’, general international law can claim at least three direct or immediate roles with regard to the ‘partial legal order’ of an international organization. First, it constitutes the ultimate source of validity of the institutional framework. Should rules pertaining to the internal law of an organization stand in violation of peremptory norms of international law, they would be void ipso jure as prescribed by Articles 53 and 64 VCLT 1969.Footnote 57 Second, nothing prevents general international law from evolving over time so as to establish more detailed and demanding requirements for the creation and operation of international organizations, just as is the case with rules of incorporation found in domestic systems. Articles 17 and 61 ARIO, for example, envisage the responsibility of organizations or member states in situations when one circumvents its international obligations by taking advantage of the separate legal personality of the other.Footnote 58 While doubts remain as to the legal pedigree of those rules and the conditions for their application, they illustrate the general law’s potential to intersect with the institutional plane as the legal system becomes more sophisticated. Third, the general law will play a crucial role in the settlement of questions arising from the withdrawal from or dissolution of an organization, that is, whenever the ‘organic link’ ceases to exist.Footnote 59 If a member is expelled from the organization or exercises a right of withdrawal, outstanding issues arising from its lapsed membership are devolved by the ‘partial legal order’ to the ‘total legal order’.
3.2.1 A monistic presumption?
At the most basic level, the terms of the relations between international legal orders are such that, subject to the limits imposed by jus cogens, the internal law of an international organization can determine the extent to which it is open to general international law. But the question arises of what role there is for general international law when – as it is often the case – the rules of the organization are silent on the matter.Footnote 60 That is, of course, a question concerning the interpretation of constituent instruments and other internal rules.
In domestic systems, general international law is typically treated as susceptible of automatic incorporation, that is, as a source of domestic law on which courts are entitled (and sometimes required) to rely without express authorization by acts passed by the legislature.Footnote 61 In fact, the only alternative to some form of automatic incorporation for international custom would be its full exclusion, since it would be unfeasible and unproductive for parliaments around the world to legislate on unwritten rules deriving from the practice and opinio juris of states. Yet, despite the rhetorical openness to custom that many domestic systems showcase, the actual application of customary rules in domestic law is fraught with difficulties, has a rather exceptional character and raises a number of legitimacy concerns.Footnote 62 As a result, domestic courts tend to be circumspect in entertaining claims based on custom.
This is where one should avoid the temptation to push an analogy between domestic law and internal law of international organizations too far, and caution international organizations against developing dualist constitutional sensibilities similar to those found among domestic courts. There are convincing reasons to regard the rules of the organization as more permeable to general international law than domestic constitutions. On the one hand, the historical, political and practical context in which the question of relations involving international legal orders is posed differs from that of the relations between international law and domestic law. Normative debates about the character of sovereignty do not have a place here, as international organizations are a direct creation of the international legal system. Likewise, most of the political values underpinning dualist positions that assert the autonomy of domestic law in relation to international law – such as democracy, separation of powers and self-determinationFootnote 63 – do not have the same import when one regards intergovernmental institutions. There is, moreover, a practical reason for constituent instruments to embrace international law. The internal law of most international organizations does not contain rules exhaustively determining how the obligations and responsibility of the organization and its members vis-à-vis each other are to be ascertained. Organizations such as the EU, which comprises a robust internal legal system overseen by courts with compulsory jurisdiction, remain the exception. In fact, the practical relevance of rules of general international law for international organizations was one of the reasons why the ILC sought to extend the scope of application of the ARIO to matters arising on the institutional plane:
even if one [considers] that the rules of the organization [are] special rules that prevailed over general international law, it must be acknowledged that they [do] not cover all questions relating to responsibility of the organization. It [is] therefore important to determine whether the international law of responsibility [provides] a backdrop that filled any gaps in the existing special rules.Footnote 64
Of course, general international law can only be relevant for relations on the institutional plane if it is capable, in light of its structure and content, of providing solutions to problems that constituent instruments and other internal rules fail to address. One of the classic arguments invoked in support of the view of that international law and domestic law must be viewed as separate legal systems is that they have different sources, comprise different subjects and regulate different subject-matters.Footnote 65 Even if one were to take this proposition at face value, it surely does not make sense of legal orders sharing an international origin. Most rules that apply in the relations between states on the international plane are capable, in structure, of playing a role in relations involving members and the organization on the institutional plane. To press the point, one just has to think of those internal rules that, in the context of the ARIO, the ILC thought would give rise to ‘international’ obligations. When a member fails to comply with a binding decision taken by a political organ of the organization, general rules regarding attribution of conduct, existence of the breach, circumstances precluding wrongfulness and the duty to provide reparation can be readily applied between organizations and members if this is not precluded by the rules of the organization.Footnote 66
On the other hand, a systemic justification for a more nuanced approach to relations between international legal orders can be found in the ILC’s Conclusions on Difficulties arising from the Diversification and Expansion of International Law adopted in 2006. The Conclusions, based on the work of a Study Group on the Fragmentation of International Law, deal with the position of so-called ‘special’ or ‘self-contained’ regimes vis-à-vis general international law.Footnote 67 These are defined as groups of ‘rules and principles concerned with a particular subject matter’, applicable as lex specialis and often having ‘their own institutions to administer the relevant rules’.Footnote 68 While the Commission did not specifically address personified entities with legal autonomy to operate on the international plane – which is puzzling given that international organizations may have the strongest claim to form self-contained regimesFootnote 69 – its analysis provides a useful starting point for articulating principles applicable to relations between international legal orders.
According to the ILC’s Conclusions, while a special regime ‘prevails over general law’ as lex specialis,Footnote 70 general law applies to fill the gaps left by the special rulesFootnote 71 and to take over from the special rules whenever the special regime ‘fails’.Footnote 72 That general international law will be applicable to issues arising from the dissolution of an international organization or from a member’s withdrawal has been noted above. But why should one presume that general law may fill gaps in the autonomous legal systems of international organizations?
The report prepared by the Study Group on Fragmentation begins by noting that ‘the claim (almost never heard) that self-contained regimes are completely cocooned outside international law resembles the views by late-nineteenth century lawyers about the (dualist) relation between national and international law’.Footnote 73 It then argues that ‘[w]hatever the validity of this view under national law, it is very hard to see how it could be applied to relations between international legal “regimes” and general international law’,Footnote 74 and concludes that:
It is in the nature of “general law to apply generally” – namely inasmuch as it has not been specifically excluded. It cannot plausibly be claimed that these parts of the law … have validity only as they have been “incorporated” into the relevant regimes. There never has been any act of incorporation. But more relevantly, it is hard to see how regime-builders might have agreed not to incorporate (that is, opt out from) such general principles.Footnote 75
This echoes Joost Pauwelyn’s suggestion that ‘in their treaty relations states can “contract out” of one, more or, in theory, all rules of international law (other than those of jus cogens), but they cannot contract out of the system of international law’.Footnote 76
Those are propositions worth considering. While the legal systems established by treaties constituting international legal subjects are arguably even more ‘autonomous’ from general international law than highly specialized treaty regimes, they are also creations of the international legal system. The institutional plane on which the relations between organizations and members take place is a derivation of the international plane where the general law applies. This is why the monistic presumption that the ILC adopted in its work on fragmentation is also relevant for the relations between general international law and the internal law of international organizations. In the debates on responsibility of international organizations at the ILC, Martti Koskenniemi, who then served as Chairman of the fragmentation group, noted that the question of relations between international legal orders ‘was clearly closely linked to the interaction between lex specialis and lex generalis’ and argued that it should not be implied that the ‘internal law’ of an organization ‘constituted a self-contained or entirely separate regime’.Footnote 77
Given that most organizations lack courts where issues of the applicability of general international law on the institutional plane can be probed, it can be hard to test the monistic presumption against their practice. But the presumption is to an extent reflected in the context of the EU, where the Court of Justice (CJEU) has been as consistent in affirming the autonomy of the Union’s legal orderFootnote 78 as in affirming its openness to international law. On the grounds that the EU ‘must respect international law in the exercise of its powers’, the Court has stated that rules of customary international law ‘are binding upon the Community institutions and form part of the Community legal order’.Footnote 79 This position is now underpinned by Article 3(5) of the Treaty on European Union, which prescribes that ‘[i]n its relations with the wider world, the Union shall contribute to the strict observance and development of international law, including respect for the principles of the United Nations Charter’.
3.2.2 Limits of the monistic presumption
3.2.2.1 Limits to the identification of competences
While there are good reasons to adopt a monistic presumption for the application of general international law on the international plane, the internal law of international organizations presents certain specificities when compared to the specialized treaty regimes on which the ILC focused its study on fragmentation. Applying the general law to special regimes normally involves construing the special rules in a way that meets the requirements of the ‘principle of harmonization’.Footnote 80 The goal is to guarantee that the special regime will interfere to the least extent possible with other rights and obligations that the parties owe to each other or third parties. But when a special regime has the effect of creating a personified entity, the application of general international law to the relations between the organization and their members may give rise to a significant constitutional concern: that the rights, obligations and capacities that the organization is capable of enjoying on the international plane are unduly invoked to expand the competences that the organization was given at the institutional level.
Finn Seyersted’s argument on the ‘inherent powers’ of international organizations illustrates the problem. More than anyone, Seyersted championed the view of international organizations as legal subjects enjoying rights, obligations, and capacities analogous to those of states.Footnote 81 He emphasized the distinction between general international law and the internal law of organizations, and convincingly argued that rights, obligations and capacities to operate on the international plane could only derive from international law. On this basis, he launched an attack at the ‘implied powers doctrine’ developed by the ICJ.Footnote 82 For Seyersted, international organizations did not need to rely on the powers expressly or implicitly provided in their constituent instruments to perform international acts. Rather, he seems to suggest, constituent instruments are only relevant insofar as they contain express prohibitions.Footnote 83
It seems that at this point Seyersted’s doctrine of ‘inherent powers’ turns into an argument on how constituent instruments must be construed.Footnote 84 But what Seyersted may have failed to appreciate is that even if the implied powers doctrine fails to explain the rights, obligations and capacities that international organizations enjoy under general international law, it may be convincing as a doctrine of constitutional interpretation on the institutional plane. As developed by international courts and tribunals, it has the merit of combining a principle of effective interpretation with a principle of legality. On the one hand, if international organizations are to perform their functions and fulfil their purposes, it is necessary that their skeletal constituent instruments be construed purposefully with the aid of teleological considerations.Footnote 85 On the other hand, just as is the case with any other institution exercising authority under a public law framework, organizations must be able to show that their acts are based on pre-defined competences.Footnote 86 This is not to say that the proposition that rights, obligations and capacities under general international law may not be a relevant factor for the interpretation of constituent instruments. In Reparation for Injuries, that the UN was deemed to be capable, as a subject of international law, of bringing international claims militated in favour of implying from the Charter the competence to perform that act.Footnote 87 Still, complex questions of constitutional interpretation should not be dealt with uncritically via the implementation of the monistic presumption or perfunctory analogies with states.
The ILC’s debate on the permissibility of countermeasures against breaches of rules of the organization provides an example on point. Following a debate as to whether the regime of countermeasures in the ARS should be extended to international organizations at all, the Commission initially adopted a provision allowing for countermeasures between organizations and members to the extent that they ‘are not inconsistent with the rules of the organization’ and ‘no appropriate means are available for otherwise inducing compliance’ of the responsible entity.Footnote 88 It followed that, under that version of the ARIO, countermeasures could have a place in relations taking place on the institutional plane. On second reading, however, the Commission changed its position. A new paragraph was added to Articles 22 and 52 ARIO to the effect that countermeasures may not be taken by organizations or their members ‘in response to a breach of an international obligation under the rules of the organization unless such countermeasures are provided for by those rules’. The Commission justified adding this default prohibition on countermeasures taken on the institutional plane on the grounds of the ‘obligation of close cooperation that generally exist between an international organization and its members’ and the ‘special ties’ between them.Footnote 89 The CJEU had adopted a similar position in Commission v. Luxembourg and Belgium.Footnote 90
The new paragraph that the ILC drafted on second reading is problematic because it is doubtful that a prohibition on countermeasures on the institutional plane can be proposed as a matter of general international law in the absence of practice and precedent pointing in that direction. Footnote 91 Rather, whether such countermeasures are allowed will depend on how the internal law of each organization is construed. However, if viewed as a guideline for constitutional interpretation, the provisions proposed by the ILC are not necessarily out of place. A provision in the ARIO that endorsed the availability of countermeasures to breaches of obligations on the institutional plane might have taken the monistic presumption too far, paving the way for arguments of questionable normative value. In fact, the position taken in the ARIO on first reading had been used as authority for the proposition that members of the UN could take lawful countermeasures against the Security Council under international law by disobeying resolutions adopted under Chapter VII of the UN Charter.Footnote 92 According to Antonios Tzanakopoulos, the Charter does not ‘explicitly prohibit countermeasures, and since they provide no appropriate means for otherwise inducing compliance of the UN with its obligation of cessation and reparation, the availability of countermeasures by [member states] against the UN must be affirmed’.Footnote 93 It is not difficult to discern the reason why the Commission would wish to distance itself from this line of argument. Rules devised for a decentralized community comprising legally autonomous entities are not always suited for application in institutional settings characterized by stronger ties of solidarity as is the case with the UN. This provides a reason to construe constituent instruments as limiting unsanctioned unilateral action rather than uncritically filling the gap with the means of ‘private justice’ found in the international law that applies to states. In the words of a member of the Commission:
international organizations [are] typically governed by special regimes and [have] renounced, at least implicitly, taking the law into their own hands. In setting up international organizations, States [create] the mutual expectation that the application of the rules of the organization [will] ultimately lead to the settlement of any dispute that might arise … That [is] true not only for organizations such as the European Community, which [has] a system of judicial remedies, but also for the United Nations and its specialized agencies. The Charter of the United Nations [has], after all, established the organized international community of States and [has] created a legal framework and procedures that risked being undermined if secondary rules which, while making sense in the context of the responsibility of reciprocally sovereign States, were formally imposed on relations between an international organization and its members.Footnote 94
3.2.2.2 The reality of institutional sensibilities and practices
While it is important not to take the monistic presumption too far, the constitutional sensibilities and practices found in certain international organizations suggest that the presumption is sometimes not taken far enough. The expansion and consolidation of ‘partial legal orders’ are often accompanied by a tendency to regard the ‘total legal order’ with a certain reserve. The judicial system of the EU provides an apt illustration. For all its commitment to upholding and promoting international law, one can identify a couple of trends in the case law of the CJEU that make the Union look suspiciously like a domestic legal system.
First, the Court of Justice has been slow to allow challenges to EU law based on rules of customary international law.Footnote 95 The Air Transport Association case provides a recent restatement of the position that custom may be ‘relied upon by an individual for the purpose of the Court’s examination of the validity of an act of the European Union’ whenever the claim has a foothold in EU law, that is:
in so far as, first, those principles are capable of calling into question the competence of the European Union to adopt that act … and, second, the act in question is liable to affect rights which the individual derives from European Union law or to create obligations under European Union law in his regard.Footnote 96
While that confirms that custom has a role to play in EU law, the standard of review which the Court proposed to apply to such challenges is very narrow:
[S]ince a principle of customary international law does not have the same degree of precision as a provision of an international agreement, judicial review must necessarily be limited to the question whether, in adopting the act in question, the institutions of the European Union made manifest errors of assessment concerning the conditions for applying those principles.Footnote 97
That shows that EU courts are hesitant to engage in full with arguments based on general international law and that they tend to defer to the interpretation and implementation of custom by the political organs of the EU. It is no wonder that, in the cases in which the standard of review of ‘manifest errors of assessment’ was applied, the CJEU found no incompatibility between custom and the internal law of the EU.
Second, there is the eminently dualistic stance adopted by the CJEU in the Kadi case. The claimants in Kadi challenged EU regulations enforcing sanctions imposed by the UN Security Council against individuals suspected of terrorism. In his submission to the Court, Advocate-General Poiares Maduro raised the question of ‘how the relationship between the international legal order and the Community legal order must be described’.Footnote 98 In his view, the Treaty on the Functioning of the European Union (as it is now known) ‘created a municipal legal order of trans-national dimensions’, the upshot being that ‘the relationship between international law and the Community legal order is governed by the Community legal order itself, and international law can permeate that legal order only under the conditions set by the constitutional principles of the Community’.Footnote 99 The Court decided in the claimants’ favour, stating that EU law was ‘an autonomous legal system which is not to be prejudiced by an international agreement’.Footnote 100 For the Court, the Union was based on ‘the rule of law’ and comprised ‘a complete system of legal remedies and procedures designed to enable the Court of Justice to review the legality of acts of the institutions’.Footnote 101 Even if the Court did not fully embrace the Advocate-General’s dualistic rhetoric, the judgment illustrates the tendency that institutions of a ‘partial legal order’ may exhibit to assert their supremacy over the ‘total legal order’ in normatively charged cases involving, for instance, fundamental rights.Footnote 102
In Kadi, the Court was not dealing with the issue of applicability of general international law in EU law, but, as Gianelli has argued, its ‘key dualist approach can hardly be limited to EU agreements’.Footnote 103 That kind of institutional sensibility is bound to be more general as it reflects ‘a choice of the EU system to open itself up to international law’, which is ‘neither absolute nor unconditional, but may require limitations’.Footnote 104 The Kadi judgment serves as a reminder not only of the role of institutions in the setting of the terms for the relations between relatively autonomous legal orders, but also of the dilemmas that officials appointed under any given legal order face when required to serve two masters.Footnote 105
With its burgeoning legal system, the EU may provide the neatest example of an institutional reality limiting the application of a monistic presumption to the institutional relations between members and their organization, but it is not the only one. Article 103 of the UN Charter functions as a broad clause affirming the supremacy of UN law over all other engagements of their members. Interestingly, Article 103 does not state that obligations under the Charter prevail over general international law, but only over ‘obligations under any other international agreement’.Footnote 106 The mainstream position is, however, that Article 103 also covers obligations by which members are bound under general international law.Footnote 107 That provides great leeway for the UNSC to depart from custom by adopting resolutions under Chapter VII of the Charter, a practice that has been a source of normative anxiety in recent times.Footnote 108 The only specific limitation on the powers of the UNSC found in the Charter is the obligation to ‘act in accordance with the Purposes and Principles of the United Nations’,Footnote 109 though it is also accepted that the UNSC is subject to jus cogens, given that the UN Charter itself derives its validity from general international law.Footnote 110 Be that as it may, applying a monistic presumption to the relations between the UN and its members when the UNSC takes action may be tricky. This is perhaps why a monistic approach has been promoted at the level of interpretation of UNSC resolutions, with commentators suggesting that ‘it is to be presumed that the [Council] does not intend to abrogate or suspend applicable international law when this is not explicit or at the very least implicit in the text of a resolution in question’.Footnote 111 That position has found favour in the case law of the European Court of Human Rights.Footnote 112
Of course, the fact that the UN has achieved virtually universal membership blurs the line between UN law and general international law. The treaty rules contained in the Charter, applicable to all states whose existence is undisputed (minus the Vatican City State), can be viewed as a de facto constitution for the international community in that they are binding across the board.Footnote 113 The special place that the Charter occupies in the international legal system is even recognized in the ARS and in the ARIO, both of which contain clauses providing that the ‘draft articles are without prejudice to the Charter of the United Nations’.Footnote 114 But the commentary to the ARIO makes the point that the saving clause is ‘not intended to exclude the applicability of the principles and rules set forth in the preceding articles to the international responsibility of the United Nations’,Footnote 115 presumably meaning that general international law continues to apply to the UN on the international and institutional planes whenever it is not displaced by the Charter. Article 103 is, in short, an instance of an internal rule promoting the autonomy of the legal order of an international organization to the point at which that legal order upheaves general international law.
4. Towards a framework for identifying the applicable law between organizations and members
When states were viewed as the sole subjects of international law, the question of how legal orders relate to one another concerned the interplay between international law and domestic law. The picture has been made more complex with the emergence of personified entities created by states, as one must now also consider the relations between legal orders sharing an international origin. I have argued in this article that, even if the internal law of international organizations derives its validity from general international law, the way in which international legal orders interact is similar to that in which international law interacts with domestic law, in that the ‘partial legal order’ established by the internal rules of the organization determines the extent to which general international law applies on the institutional plane. That is a consequence of the fact that general international law contains very few rules, if any, concerning the internal functioning of international organizations. It is thus a mistake to assume, as the ILC sometimes does, that customary rules always apply between international organizations and their members.
That does not mean, however, that general international law has no part to play. For one, a distinction must be made between relations taking place on the international plane and those taking place on the institutional plane. In the former, general international law applies by default to the extent that it is not displaced by lex specialis. And even on the institutional plane there are good reasons to postulate a monistic presumption for the application of general international law when the internal rules of an organizations are silent. That presumption is justifiable on systemic, practical and normative grounds. Yet, the presumption will play different roles in different organizations as it gets co-opted and domesticated by the political realities and institutional sensibilities prevailing in each of them.
It should be fitting to conclude this article with an illustration of how the framework to identify the applicable law between organizations and members sketched here helps structure legal analysis.Footnote 116 Consider an international organization established by a constituent instrument which provides that headquarters agreements may be concluded with member states, allocating to the Secretary-General the competence to negotiate, adopt and express consent to the text after securing the approval of the organization’s Assembly. If the Secretary-General were to conclude a headquarters agreement with a member state without the Assembly’s approval, the other members might wish to look into available legal options to challenge that transaction. They might, for example, wish to know whether the treaty is voidable. They might wish to know, in addition, whether disciplinary action can be taken against the imprudent Secretary-General, and what measures can be taken against the organization or the member state that agreed to the irregular treaty.
In looking at those scenarios, a legal advisor to the member states would have to identify the rules that apply between the organization and its members. Considering the potential claim that the treaty concluded without the approval of the Assembly is voidable, she would first have to characterize the issue as one arising on the international plane, for the treaty was formed when the organization and the host state expressed their consent on the international plane and derives its binding force from the principle pacta sunt servanda. The rule in Article 46(2) VCLT 1986 (assuming that it reflects customary international law) would then apply, with the effect that the organization can only claim that ‘its consent to be bound by a treaty has been expressed in violation of the rules of the organization regarding competence to conclude treaties’ if ‘that violation was manifest and concerned a rule of fundamental importance’. It would not be sufficient to show that the Secretary-General acted ultra vires or that a provision of the constituent instrument of the organization was breached. Rather, it would be necessary to consider the significance of that breach under the rules laid down in the general international law of treaties. An imaginative legal advisor might seek to argue that the constituent instrument creates a special rule concerning the expressing of consent to headquarters treaties which would displace the general rules of international law applicable between the organization and its members on the international plane. But it should be clear that the methodological standpoint in this scenario is that the rules of general international law apply between the organization and its members by default. Arguments aimed at displacing those rules will seek to show that the provisions of the constituent instrument constitute lex specialis applicable between the parties on the international plane.
Considering whether the organization may take disciplinary measures against the Secretary-General or which measures can be taken against the organization or the recalcitrant member state, the legal advisor would first have to classify the scenario as one of relations arising on the institutional plane. She would thus advise the members that the default rules are to be found in the internal law of the organization, and that general international law can only be invoked as a source of rights and obligations to the extent that internal law allows. If the constituent instrument were silent on the issue and she was persuaded by the appropriateness of adopting a monistic presumption as argued in this article, she might conclude that standards from, say, the international law of human rights can be invoked as constraints to the range of possible disciplinary measures to be taken against the Secretary-General. The availability of international law countermeasures against the recalcitrant member state would be more doubtful given that, as discussed above, that kind of unilateral action may not sit comfortably with the logic of co-operation that defines the institutional plane – she might well find them to be incompatible with the internal law of the organization. Whichever specific arguments are made, the methodological standpoint in this scenario is that the analysis must start with the rules of the organization, and that any attempts to rely on general international law will need to be anchored in an argument that shows that its incorporation is permissible under such rules.
In conclusion, the question of the extent to which general international law applies between international organizations and their members can present itself in multifaceted scenarios that require careful unpacking and methodological rigour. In dealing with particular cases, it is important to know which questions to ask, while maintaining a structural understanding of an international legal system that keeps growing increasingly intricate. This is where, I hope, the present analysis can make a contribution.
