2.1 The Articles on the Responsibility of States for Internationally Wrongful Acts

Before assessing the practice of the ICJ, it is necessary to briefly address the contribution of the ILC through its 2001 Articles on the Responsibility of States for Internationally Wrongful Acts. The Articles – some of which codify existing rules of international law, others of which seek progressively to develop the law – not only reflect the views of the ICJ in its case law prior to 2001 but also serve as a benchmark against which to assess its subsequent decisions.Footnote ¹⁴

The Articles are tailored to address a variety of primary obligations, which ‘may be owed to another State, to several States, or to the international community as a whole’.Footnote ¹⁵ Within which of these categories a particular obligation falls, and whether it gives rise to a right erga omnes to invoke responsibility for its breach, depends on the interpretation of the relevant rule.Footnote ¹⁶ Discarding an earlier preference for a broad definition of ‘injury’, which would have provided a unified basis for the invocation of responsibility, the question of a state’s right to invoke the responsibility of a breaching state eventually took the form of Articles 42 and 48 of the ARSIWA.Footnote ¹⁷ Article 42Footnote ¹⁸ defines an ‘injured state’ as a state to which the obligation breached is owed, either individually, in accordance with Article 42(a), or as part of a group of states or of ‘the international community as a whole’, in accordance with Article 42(b), which entitles a state to invoke the responsibility of the breaching state if the breach ‘specially affects’ itFootnote ¹⁹ or ‘is of such a character as radically to change the position of all the other States to which the obligation is owed’.Footnote ²⁰ Critically, an injured state is entitled not only to invoke the responsibility of another state for its breach of a primary obligation but also to resort to a variety of countermeasures.Footnote ²¹

Complementing Article 42, Article 48 permits ‘any State other than an injured State’ to invoke the responsibility of a breaching state if one of two conditions specified under Article 48(1) is met:

1. (a) the obligation breached is owed to a group of States including that State, and is established for the protection of a collective interest of the group; or

2. (b) the obligation breached is owed to the international community as a whole.Footnote ²²

While a state acting under Article 48(1)(a) does so ‘in its capacity as a member of a group of States to which the obligation is owed’, addressing the breach of obligations erga omnes partes,Footnote ²³ a state acting under Article 48(1)(b) does so ‘as a member of the international community as a whole’, addressing the breach of obligations erga omnes.Footnote ²⁴ Conceptually, there is no distinction between the two categories.Footnote ²⁵ Article 48 being complementary to Article 42, the Commission did not rule out the possibility of an injured state invoking responsibility for the breach of an obligation erga omnes or erga omnes partes.Footnote ²⁶ The inclusion of Article 48 – a progressive development of the lawFootnote ²⁷ – was intended mainly to address those obligations in respect of which there may be no injured state to invoke responsibility for a breach. For the Commission, it was ‘highly desirable’ that states other than an injured state be entitled to take some more limited measures in order ‘to protect the community or collective interest at stake’.Footnote ²⁸ Accordingly, a state is entitled to seek cessation of the breach and perhaps also assurances and guarantees of non-repetition, under Article 48(2)(a), but also reparation ‘in the interest of the injured State or of the beneficiaries of the obligation breached’, under Article 48(2)(b).Footnote ²⁹ The effectiveness of Article 48 in filling this gap of enforceability is, however, limited by the decoupling of the entitlement to invoke responsibility, on the one hand, and the availability of countermeasures, on the other. Under international law as it then stood, and as reflected in the Articles, only injured states are entitled to resort to countermeasures. This limitation vis-à-vis states acting under Article 48 is anticipated by Article 54, the savings clause permitting states other than injured states to take ‘lawful measures’, whatever they may be,Footnote ³⁰ to ‘ensure cessation of the breach and reparation in the interest of the injured State or of the beneficiaries of the obligation breached’. Absent a rule of international law permitting the use of countermeasures by states under Article 48, ‘[t]he pragmatic compromise – and, indeed, the only possible political solution – was to defer debate to another day’.Footnote ³¹

The Commission having restricted the scope of the ARSIWA to secondary obligations, the Articles do not themselves identify the primary obligations that may qualify as obligations erga omnes or erga omnes partes for the purpose of Articles 48. That task is effectively left to the ICJ, which had already offered some illustrations before 2001. In subsequent practice, the Court has also engaged with the question of the invocation of responsibility for the breach of obligations erga omnes, including through the conferral of locus standi, even if it has not addressed Article 48 by name.

2.2 The practice of the International Court of Justice

The decision of the Permanent Court of International Justice (PCIJ) in SS Wimbledon in 1923 was the first articulation of the expansive position later expressed in Article 48(1)(a) of the ARSIWA.Footnote ³² In that case, the UK, France, Italy, and Japan had complained of a breach by Germany of its obligations under the Treaty of Versailles when it denied the SS Wimbledon – a vessel registered to the UK and chartered by a French company – access to the Kiel Canal. On the question of each state’s standing to institute the proceedings, the Court observed that Italy and Japan also ‘had a clear interest in the execution of the provisions relating to the Kiel Canal’ since they ‘possess[ed] fleets and merchant vessels flying their respective flags’.Footnote ³³ Notwithstanding the absence on their respective parts of ‘any pecuniary interest’ in the matter, the Court endorsed an expansive reading of the jurisdiction clause in Article 368(1) of the Treaty, which conferred on ‘any Interested Power’ a right to institute proceedings before it.Footnote ³⁴

In contrast to the PCIJ, the ICJ in the earliest proceedings in which the question of standing to bring a dispute in respect of collective interests was at issue, namely the South West Africa Cases, wavered. Following the institution by Ethiopia and Liberia of proceedings against South Africa in respect of the latter’s alleged violation of its mandate for South West Africa under the League of Nations, it fell to the Court to address the question of Ethiopia and Liberia’s ‘legal right or interest regarding the subject matter of their claim’.Footnote ³⁵ In its initial decision of 1962, the Court endorsed the applicants’ standing to bring the dispute as member states of the League of Nations with ‘a legal right or interest’ in South Africa’s compliance with its obligations ‘towards the inhabitants of the Mandated Territory, and towards the League of Nations and its Members’.Footnote ³⁶ Conversely, based on its subsequent assessment of the Covenant of the League of Nations and the instrument of mandate for South West Africa, the Court found in its final decision of 1966 that South Africa’s obligations in respect of the mandate had been owed to the League of Nations as a whole and not to its member states individually.Footnote ³⁷ It relied inter alia on a restrictive reading of the jurisdiction clause specified in Article 7(2) of the instrument of mandate, which in its view did not confer upon member states a substantive right to invoke the responsibility of the mandatory.Footnote ³⁸ Accordingly, neither the Covenant nor the instrument conferred on the former member states of the League of Nations a right of recourse to the ICJ.Footnote ³⁹ The Court did not, however, exclude in principle the existence under international law of a right of standing, absent injury, where ‘such rights or interests’ are ‘clearly vested in those who claim them, by some text or instrument, or rule of law’.Footnote ⁴⁰ At the same time, it rejected in broader terms the resort by states to an ‘actio popularis’, which it considered ‘[wa]s not known to international law’ at the time.Footnote ⁴¹

What followed the ICJ’s 1966 decision in the South West Africa cases was the apparent reversal by the Court of the restrictive position it ultimately took on the issue of standing. The Court’s dictum in its Barcelona Traction decision of 1970, which is widely considered to be reflected in Article 48(1)(b) of the ARSIWA,Footnote ⁴² is as follows:

Going beyond the treaty-based disputes that had previously been at issue in SS Wimbledon and the South West Africa cases, in which contexts it was primarily the interpretation of relevant jurisdiction clauses that had been at issue, the Court recognized a category of ‘obligations erga omnes’Footnote ⁴⁴ under both treaty law and general international law,Footnote ⁴⁵ even if it did not elaborate upon the legal basis for their existenceFootnote ⁴⁶ and notwithstanding the fact that the violation of obligations erga omnes had not been at issue in Barcelona Traction.Footnote ⁴⁷

A series of subsequent disputes provided the Court the opportunity to elaborate upon the arguably broad concept it had introduced in Barcelona Traction. This is not to say that the Court always took the opportunity to do so. In Nuclear Tests (Australia v. France), for instance, the majority did not address the question of Australia’s standing to bring a dispute in respect of France’s future compliance with what Australia characterized as the erga omnes prohibition of atmospheric nuclear tests under customary international law since, in the view of the Court, France had in fact undertaken an obligation not to conduct further tests. Judge ad hoc Barwick was alone in endorsing, if only in principle, a right of standing in respect of obligations erga omnes that confers upon individual states, such as Australia, a corresponding right to compliance.Footnote ⁴⁸ Conversely, Judge de Castro rejected the contention, including on the basis that the dictum in Barcelona Traction should be taken ‘cum grano salis’.Footnote ⁴⁹ So also in Bosnian Genocide, only Judge Oda obliquely addressed the issue of standing, asserting that the erga omnes partes nature of the obligations under the Genocide Convention did not mean that responsibility for a breach could be invoked ‘in inter-State relations’, including by instituting proceedings at the ICJ.Footnote ⁵⁰ In his view, the alleged breach by a state party of an obligation erga omnes partes does not automatically give rise to a dispute as to the ‘interpretation, application or fulfilment’ of the treaty with another state party.Footnote ⁵¹ For a dispute to exist, the latter must demonstrate the resultant infringement of its rights.Footnote ⁵² For Judge Oda, this was doubtful, since the obligations erga omnes enumerated in the Genocide Convention were owed principally to individuals and groups. Their breach was thus better addressed by means other than adjudication.Footnote ⁵³

Similarly, when in 1995 Portugal invoked Australia’s optional clause declaration under Article 36(2) of the ICJ Statute to bring a case against Australia pertaining inter alia to the violation of the right of the people of Timor-Leste to self-determination – arguably an obligation erga omnes – it fell to the Court to determine whether Portugal enjoyed standing to initiate the proceedings. The Court in East Timor did not address Australia’s argument that Portugal did not have ‘a sufficient interest of its own to institute the proceedings’ and thus lacked locus standi.Footnote ⁵⁴ Instead, the decision turned on whether the Court could adjudicate the dispute without the participation of Indonesia, which had not consented to the exercise of the Court’s jurisdiction but whose rights and obligations were, in Australia’s view, at issue. While endorsing the erga omnes nature of the obligation to respect the right of self-determination,Footnote ⁵⁵ the Court rejected Portugal’s contention that its characterization as such meant that the indispensable third party rule, which called for Indonesia’s participation, could be discarded.Footnote ⁵⁶ As the Court explained, ‘the erga omnes character of a norm and the rule of consent to jurisdiction are two different things’.Footnote ⁵⁷ A different conclusion was reached by Judge Weeramantry, who dissented on the basis that ‘the practical operation’ of obligations erga omnes would be restricted by the requirement of consent such that the former would be ‘substantially deprived of its effectiveness’.Footnote ⁵⁸ The Court having affirmed the requirement of consent to jurisdiction, the decision lent no further clarity as to whether, conditional upon Indonesia’s consent, the violation of an obligation erga omnes would confer a right of standing on Portugal or on any other state.Footnote ⁵⁹

The clearest affirmation to date of a right of standing in respect of violations of at least obligations erga omnes partes came in the Court’s 2012 decision in Questions relating to the Obligation to Prosecute or Extradite (Belgium v. Senegal).Footnote ⁶⁰ The relevant question in that case was whether Belgium could bring a dispute against Senegal, first, for alleged violations under the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (‘Torture Convention’), and secondly, under customary international law, including in respect of the obligation to prosecute crimes against humanity, genocide, and war crimes.Footnote ⁶¹ When it came to Senegal’s alleged violations of the Torture Convention, Belgium argued not only that it enjoyed locus standi as a state party to the treaty but also that it had a special interest in the matter.Footnote ⁶² The Court, however, focused its attention exclusively on the former submission. Relying on the object and purpose of the Convention, it agreed that all states parties, including Belgium, had a legal interest in compliance with what it described as the obligations erga omnes partes articulated therein.Footnote ⁶³ Accordingly,

It was thus not necessary to determine whether Belgium also had a special interest in the matter.Footnote ⁶⁵ Judge Xue and Judge ad hoc Sur, dissenting, questioned the majority’s reliance on the notion of obligations erga omnes partes to establish Belgium’s standing, an approach which Judge Xue considered to be ‘abrupt and unpersuasive’Footnote ⁶⁶ and which, in Judge ad hoc Sur’s opinion, ‘ha[d] been produced like a rabbit from a magician’s hat’.Footnote ⁶⁷ Sceptical of the weight assigned to the dictum in Barcelona Traction, Judge Xue asserted that the mere identification of a category of collective interests in that case did not necessarily confer a right of standing on states individually to invoke responsibility for their breach.Footnote ⁶⁸ She drew the same distinction when it came to the majority’s characterization of relevant treaty rules as obligations erga omnes partes:

Judge Xue also rejected the majority’s suggestion that the concept of obligations erga omnes partes was necessary in cases in which ‘no State would be in the position to make … a claim’.Footnote ⁷⁰ For her, the non-adjudicatory accountability mechanisms specified in the Convention, including the role of the Committee against Torture, ‘are designed exactly to serve the common interest of the States parties in the compliance with the obligations under the Convention’.Footnote ⁷¹ In the same vein, and relying once again on the text of the treaty, both dissenting judges claimed that since states parties could make reservations to exclude the jurisdiction of the ICJ in respect of their treaty obligations, there could be no generalized right of standing for each of them to invoke, in the collective interest, responsibility for the breach of those obligations.Footnote ⁷² That is, ‘the parties do not form a single homogeneous group which assumes the same obligations and can claim the same rights’.Footnote ⁷³ When it came to Senegal’s obligations under customary international law, the opportunity to affirm locus standi in respect of obligations erga omnes arising under customary international law was missed since the Court found that a dispute with Belgium did not exist in respect of those obligations.Footnote ⁷⁴

Of more recent vintage is the 2014 Whaling in the Antarctic (Australia v. Japan: New Zealand Intervening)Footnote ⁷⁵ decision in which the respondent state, Japan, did not challenge Australia’s standing to bring the dispute. The absence of any discussion on the point is striking since Australia was alleging violations by Japan of the International Convention for the Regulation of Whaling and other treaty obligations without any suggestion of injury on its part.Footnote ⁷⁶ Given the proximity of the proceedings to the Court’s earlier decision in Obligation to Extradite, Japan’s contestation of the jurisdiction of the Court,Footnote ⁷⁷ and the parties’ reliance on the object and purpose of the Convention to support competing interpretations on the merits,Footnote ⁷⁸ the Court’s decision not to determine whether the Convention established obligations erga omnes partes in order to establish standing – as it had done in Obligation to Extradite – is unexpected, if not anomalous. Presumably, the Court accepted the position that Australia had purported to act in the collective interestFootnote ⁷⁹ and on that basis engaged Japan’s responsibility for the breach of obligations erga omnes partes.Footnote ⁸⁰

Another recent case of a state seeking to act in the collective interest was the Marshall Islands’ institution of proceedings against a number of states in respect of their alleged violations of the integral obligation, arising variously under treaty law and customary international law, to negotiate a move towards nuclear non-proliferation. Contrary to the Whaling decision, the three decisions of 2016, issued on the basis of the optional clause declarations of the UK, India and Pakistan respectively,Footnote ⁸¹ endorsed the existence of a collective interest in nuclear non-proliferation but found, as Judge Oda had in Bosnian Genocide, the absence of a bilateral dispute between the parties necessary for the exercise of the Court’s jurisdiction.Footnote ⁸² As such, the question of standing did not arise.Footnote ⁸³ Each dissenting judge challenged what he considered to be the majority’s excessively formalistic approach to a ‘dispute’. In Judge Crawford’s view, for example, the adjudication of a multilateral dispute of this kind, while ‘ultimately be[ing] fitted within the bilateral mode of dispute settlement’, does not require that the ‘underlying relations’ between the parties be ‘bilateral ab initio’.Footnote ⁸⁴ Judge Tomka added that the dispute would have in any event been rendered inadmissible due to the absence from the proceedings of other nuclear weapons states with which the UK, India and Pakistan were obliged to negotiate, suggesting ultimately that another forum was more appropriate.Footnote ⁸⁵

Most recently, The Gambia in its institution in 2019 of proceedings against Myanmar in Application of the Convention on the Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar) did so explicitly on the basis of ‘the erga omnes and erga omnes partes character of the obligations that are owed under the Genocide Convention’.Footnote ⁸⁶ Accordingly, The Gambia sought

While in the Whaling and Marshall Islands cases it would have proved necessary for the Court – had it addressed the issue of standing – to establish the existence of a collective interest in compliance, The Gambia’s right of standing was relatively secure. The Court had already affirmed, on more than one occasion, the erga omnes partes nature of the obligations arising out of the Genocide Convention.Footnote ⁸⁸ In Barcelona Traction, it had offered as an example of obligations erga omnes the obligations arising out of the prohibition of genocide under international law.Footnote ⁸⁹ In Obligation to Extradite, the Court’s conferral of a right of standing vis-à-vis obligations erga omnes partes under the Torture Convention had been based in part on the treaty’s similarity, in its view, with the Genocide Convention.Footnote ⁹⁰ If this were not enough, both decisions referred back to the 1951 advisory opinion Reservations to the Convention on the Prevention and Punishment of the Crime of Genocide in which the Court, speaking of the Genocide Convention, remarked:

These decisions together provided the basis for the Court’s provisional affirmation of The Gambia’s standing in its order for provisional measures on the ground that ‘any State party to the Genocide Convention, and not only a specially affected State, may invoke the responsibility of another State party’.Footnote ⁹² Accordingly, the Court rejected Myanmar’s counter-arguments. It had been Myanmar’s contention that, although it had consented to the jurisdiction of the Court by its acceptance of the compromissory clause in Article IX of the Genocide Convention, it had made a reservation to exclude the application of Article VIII of the Convention, which in its view was the provision that actually permitted the Court to render a decision as an organ competent to take appropriate ‘action’. Conferring a right of standing on The Gambia would thus vitiate the requirement of Myanmar’s consent to what it considered ultimately to be the application of Article VIII.Footnote ⁹³ The Court also rejected Myanmar’s argument that locus standi was conferred only on specially affected states, such as Bangladesh, and that permitting the institution of proceedings by The Gambia ‘would represent a major inroad into fundamental principles concerning the consensual nature of the Court’s jurisdiction’.Footnote ⁹⁴ If only specially affected states were entitled to standing before the Court, and it was only Bangladesh that was, in Myanmar’s view, entitled to initiated the proceedings, the Court would have been unable to exercise its jurisdiction owing to Bangladesh’s reservation to Article IX of the Convention, which effectively made the Court’s jurisdiction conditional upon Myanmar’s consent.Footnote ⁹⁵ Judge Xue, consistently with her dissent in Obligation to Extradite, challenged the majority’s reasoning on the question of standing. She sought once again to separate the collective interest of states parties under the treaty, on the one hand, and standing to institute proceedings before the Court, on the other. In her view:

On the question of enforcement, Judge Xue, like Judges Oda and Tomka had previously done, emphasized the existence of alternative mechanisms for addressing breaches of the Genocide Convention, including through the architecture of the UN.Footnote ⁹⁷

In sum, the ICJ has in several of its decisions affirmed the existence of the category of obligations erga omnes it had proposed in Barcelona Traction. In doing so, the Court has shed light on what these collective obligations may be, in particular by reference to the object and purpose of multilateral treaties, such as the Genocide Convention, as well as in respect of relevant rules of customary international law, as with the right to self-determination. The Court has also recognized a right of standing to enforce obligation erga omnes, even if its conferral of locus standi has in practice been limited to obligations erga omnes partes arising under the multilateral treaties which have been the subject of the cases before it. When it has come, however, to addressing the consequences of its conferral of a right of standing to invoke responsibility for the breach of obligations erga omnes, the Court’s engagement with relevant issues has been somewhat more limited. Various issues remain to be addressed, perhaps in the judgment on the merits in Rohingya Genocide.

3.1 Obligations erga omnes arising under customary international law

The earlier decisions of the PCIJ and the ICJ notwithstanding, it is often suggested that the ICJ’s dictum in Barcelona Traction was the starting point for the recognition and enforcement of community interests in international law.Footnote ¹⁰⁰ On an expansive reading of that decision, the Court was responsible for not only creating the category of obligations erga omnes but also ‘describ[ing] specific features of the secondary rules governing the invocation of responsibility for violations of obligations called “erga omnes”’.Footnote ¹⁰¹ Even those, like Judges de Castro, Oda, and Xue, who question the weight that has since been assigned to the Court’s statements in Barcelona Traction, can no longer rely on a more restrictive reading to exclude locus standi vis-à-vis breaches of obligations erga omnes. Their position, articulated in Judge de Castro’s statement in Nuclear Tests, below, has been clearly rejected in the subsequent practice of the Court:

Any remaining doubt as to the connection between the recognition of obligations erga omnes, on the one hand, and locus standi, on the other, has been dispelled by the more recent jurisprudence of the Court in Obligation to Extradite and Rohingya Genocide.Footnote ¹⁰³ The same position was effectively taken in the Whaling case,Footnote ¹⁰⁴ with one commentator observing that the decision ‘could be seen as a sequel to’ the decision in Obligation to Extradite.Footnote ¹⁰⁵

Even so, the contribution of the Court’s practice on the point is not unqualified. While Barcelona Traction identified obligations erga omnes as existing under both multilateral treaties and general international law, giving rise in principle to locus standi in respect of both treaty law and customary international law, the Court did not ‘announc[e] a new rule as much as a category, a general idea, an alternative way of establishing legal relations in international law’.Footnote ¹⁰⁶ Viewed in this light, the subsequent practice of the Court, which has so far recognized a right of standing in respect only of breaches of obligations erga omnes partes under multilateral treaties, cannot necessarily be taken to represent the endorsement of a broader right of standing also in respect of obligations erga omnes under customary international law.Footnote ¹⁰⁷ While there is no qualitative distinction between obligations erga omnes and erga omnes partes, nor between states’ interests in compliance with collective obligations under treaty law and customary international law respectively, the Court has simply not been required, in its decisions to date, to address the issue of standing by reference to customary international law. This has been the case even in disputes in which the Court acknowledged the existence of obligations erga omnes under customary international law, such as in East Timor and Obligation to Extradite.Footnote ¹⁰⁸ To the extent that the Court might address the breach of obligations erga omnes arising under customary international law in the future, states’ willingness to bring a dispute on this basis alone and the Court’s willingness to confer locus standi might both be made more difficult by the absence of a textual hook – such as a jurisdiction clause or the object and purpose of a treaty – on which to hang such a right.Footnote ¹⁰⁹

3.2 The enduring requirement of consent to jurisdiction

The Court’s conferral of locus standi to invoke the responsibility of a state in breach of an obligation erga omnes is conditioned upon the requirement of the breaching state’s consent to the contentious jurisdiction of the Court, whether through the issuance of a declaration under Article 36(2) of the Statute, in accordance with a treaty’s compromissory clause, or by special agreement. The satisfaction of this procedural requirement is usually regarded as a condition precedent in discussions of standing.Footnote ¹¹⁰ Accordingly, ‘the erga omnes concept does not affect the consensual character of the Court’s jurisdiction’.Footnote ¹¹¹ Yet others seek to overcome what they perceive to be a barrier to the effectiveness of obligations erga omnes by suggesting that the Court, in issuing its dictum in Barcelona Traction, ‘could not [have] overlook[ed] the possible consequences of [obligations erga omnes] for the jurisdiction of the Court’.Footnote ¹¹² Accordingly, in the words of Judge Weeramantry, the enforcement of obligations erga omnes, ‘which transcend the individual rights and obligations of litigating States’, requires that international law ‘look[s] beyond procedural rules fashioned for purely inter partes litigation’.Footnote ¹¹³ This conflict between the effectiveness of obligations erga omnes and the requirement of consent to jurisdiction arises not only in the application of the indispensable third party rule, discussed in East Timor, but also in respect of a reservation purporting to exclude the application of a treaty’s compromissory clause and the adjudication of the dispute in the collective interest absent the participation of an injured state.

When it came to the application of the indispensable third party rule, the majority of the Court in East Timor concluded that, where the legal interests of a third state constitute the subject-matter of the dispute, the requirement of that state’s consent to jurisdiction is essential even where the enforcement of obligations erga omnes is at stake.Footnote ¹¹⁴ The Court rightly carved out of an otherwise expansive right of standing disputes in respect of which an indispensable third party state has not consented to its jurisdiction.Footnote ¹¹⁵ Its decision to do so nevertheless proved controversial. According to one commentator, ‘it is ironic that the very Court that spelled out the concept [of obligations erga omnes] in the first place has now subjected it to the procedural rigours of traditional bilateralism’.Footnote ¹¹⁶ Similarly, for Judge Weeramantry, applying the indispensable third party rule in respect of obligations erga omnes allows the respondent state to ‘plead another State’s responsibility as an excuse for its own failure to discharge its own responsibility’.Footnote ¹¹⁷ This is only true to the extent that the responsibility of the respondent state for the breach of an obligation erga omnes cannot be determined independently of the responsibility of a state not party to the proceedings for the breach of the same obligation.Footnote ¹¹⁸ In all cases in which obligations erga omnes require that states take action individually, the indispensable third party rules is unlikely to apply.

A second, analogous manifestation of the conflict between the enforcement of obligations erga omnes and the requirement of consent to jurisdiction, pertaining specifically to multilateral treaties, is the issuance by states parties of reservations purporting to exclude the jurisdiction of the Court in respect of the obligations erga omnes partes arising thereunder. For its part, the Court has rejected the suggestion that a reservation to a treaty’s compromissory clause is impermissible when it comes to the enforcement of obligations erga omnes partes.Footnote ¹¹⁹ As emphasized by Judge Xue in Obligation to Extradite, the blanket conferral of standing on states parties by virtue of their status as such is therefore ineffective to the extent that the breaching state party has excluded either the substantive obligation that is the subject of the dispute, precluding the possibility of a breach in the first place,Footnote ¹²⁰ or the application of the compromissory clause conferring jurisdiction upon the Court.Footnote ¹²¹ In the same case, Judge ad hoc Sur explained that

A generalized right of standing for states parties is thus limited by the extent to which states parties may be permitted to exclude, by reservation, the application of the Treaty’s compromissory clause and therefore the jurisdiction of the Court. This is not to endorse, however, the position taken by Judges Xue and Sur that the permissibility of a reservation to exclude the application of the treaty’s compromissory clause likewise excludes locus standi for the enforcement of obligations erga omnes arising under the treaty even where no reservation has been made.Footnote ¹²³

Against this backdrop, it is sometimes asserted that certain obligations, including obligations erga omnes, ‘constitute an indivisible whole’, thereby precluding reservations which would run counter to the collective interest.Footnote ¹²⁴ Put differently, where multilateral treaties impose obligations erga omnes partes which ‘cannot possibly be … effected on a bilateral basis’, reservations – which represent an essentially bilateral operation of multilateral treaties – become impermissible.Footnote ¹²⁵ Whether this logic can be extended to rule out reservations that withhold consent to the application of the treaty’s compromissory clause, and therefore the jurisdiction of the Court, remains doubtful.Footnote ¹²⁶ The better approach, and one which does not easily dispense with the requirement of consent, is the express articulation in multilateral treaties encompassing obligations erga omnes partes of a rule excluding reservations to its compromissory clause, albeit at the potential cost of limiting acceptance by states of the treaty. To the extent that states are bound by a treaty’s compromissory clause, the exercise of the Court’s jurisdiction will depend on its wording. So far, only Judge Oda has taken a position on the issue, suggesting that the alleged violation by a state of an obligation erga omnes partes does not necessarily give rise to a dispute as to the application or interpretation of a treaty.

Finally, in Rohingya Genocide, the question of consent arose in a slightly different constellation. According to Myanmar, had Bangladesh instituted the proceedings as a specially affected and therefore injured state,Footnote ¹²⁷ the proceedings would have been precluded – per Bangladesh’s own exclusion of compulsory jurisdiction under Article IX of the Genocide Convention – by the requirement of Myanmar’s consent to jurisdiction. In Myanmar’s view:

The Court in its order for provisional measures did not address the issue, but appears to have endorsed the position taken by the dissenting Judge Weeramantry in East Timor, that ‘[a]n erga omnes right is … a series of separate rights erga singulum’, which ‘are in no way dependent one upon the other’.Footnote ¹²⁹ Indeed, if consent to the jurisdiction of the Court exists in respect of the dispute between The Gambia and Myanmar, it is irrelevant whether Myanmar would have withheld its consent in respect of a potential dispute with Bangladesh or any other state. A fuller appraisal of the approach effectively taken by the Court requires the consideration of the related question of the permissibility of standing in the collective interest where an injured state may be able itself to institute proceedings.

3.3 The indispensable injured state?

Myanmar’s consent-based objection to the exercise of the Court’s jurisdiction in Rohingya Genocide, while unconvincing, raises the related question of whether a state other than an injured state may institute proceedings before the Court where an arguably injured state may be able itself to do so.Footnote ¹³⁰ The issue raises practical concerns about whether an injured state is best placed to represent the collective interest,Footnote ¹³¹ or if its proximity to the breach or the breaching state creates political risks that prevent it from acting effectively or at all.Footnote ¹³² In this respect, Rohingya Genocide is clearly distinguished from the Court’s prior cases since Barcelona Traction, in which the states instituting the proceedings did so both in the collective interest and on the basis of injury, as in East Timor and Obligation to Extradite, or where there was simply no injured state to speak of, as in the Whaling case. Endorsing The Gambia’s right to institute the proceedings in the collective interest, the Court rejected Myanmar’s contention that it was only an allegedly injured state that had a right to do so. In this regard, the Court seems tentatively to have aligned itself with the ILC’s progressive development of the law on the issue. While emphasizing the significance of Article 48 of the ARSIWA in situations in which there is no injured state to invoke responsibility, the Commission did not eventually limit the scope of the provision in this way. Instead, Article 48(2)(b) permits a state other than an injured state to claim reparation ‘in the interest of the injured State or of the beneficiaries of the obligation’. In accordance with the ILC’s approach, it was permissible, in the view of the Court, for The Gambia to bring the dispute without any assessment of whether there was in fact an injured state with more firm standing upon which to do so.

Perhaps in the interest of expediency in awarding provisional measures, the Court did not, in its broad-brush endorsement of this position, engage with the consequences of affording states a right of standing even where an injured state may be able itself to act. It did not even address the question of whether Bangladesh may be considered to be a state specially affected, and therefore injured, by Myanmar’s alleged violations of the Genocide Convention.

The consequences of the position effectively taken by the Court pertain first to the provision of remedies. On the one hand, compliance with certain obligations having been recognized to be in the collective interest, cessation of the breach and assurances and guarantees of non-repetition may no longer be regarded as remedies that are available exclusively to the injured state.Footnote ¹³³ On the other hand, where reparation is specifically sought in the interest of the injured state (within the meaning of Article 48(2)(b)), the participation in some form of the injured state proves necessary.Footnote ¹³⁴ Were these remedies to be conferred without the participation in the proceedings of the injured state, the indispensable third party rule might be rendered inapplicable to the extent that the provision of remedies for the breach of an obligation erga omnes may be said to constitute the subject-matter of the dispute. Where, however, the state instituting the proceedings does not purport to act in the interest of an injured state (as with The Gambia), further clarification is warranted as to the preclusive effects of the Court’s decision, that is, the application or not of the principle of res judicata to subsequent claims by the injured state or other states,Footnote ¹³⁵ in particular where the remedies awarded by the Court go beyond cessation and assurances and guarantees of non-repetition.Footnote ¹³⁶ For its part, the ILC did not overlook that the entitlement of a state acting under Article 48 of the ARSIWA ‘will coincide with that of an injured State in relation to the same internationally wrongful act’, but did not conclusively address the issue.Footnote ¹³⁷ Presumably, the question is one of claim preclusion and not the stricter test of identity – including the identity of the parties – usually required for the operation of res judicata in international law. In accordance with the view expressed by Judge Weeramantry and seemingly adopted also by the majority in Rohingya Genocide, if erga omnes rights operate erga singulum then so does the principle of res judicata, suggesting that the principle will only apply to the same parties, that is, with conclusive but not preclusive effects.Footnote ¹³⁸

Secondly, although not relevant to the proceedings in Rohingya Genocide, complications may also arise from the injured state’s loss of the right to invoke responsibility due to its waiver or acquiescence in the lapse of the claim,Footnote ¹³⁹ warranting clarification as to whether other states acting in the collective interest preserve the right, erga singulum, to invoke responsibility for the breach.Footnote ¹⁴⁰ The primary justification to date for the Court’s conferral of a right of standing being to fill a gap in enforcement,Footnote ¹⁴¹ a proposal that itself remains contentious, further discussion of the consequences of its permissive approach to the institution of proceedings in the collective interest – even where an injured state may be able itself to do so – is necessary.

3.4 Third state intervention

At the time of writing, The Maldives, Canada, and The Netherlands have expressed an intention to intervene in the proceedings in Rohingya Genocide.Footnote ¹⁴² Were these or other states to intervene as states parties to a treaty whose construction is at issue, the question of their participation is straightforward: Article 63(2) of the Statute confers upon all states parties a right to intervene in the proceedings on the condition that the construction given by the Court to the treaty ‘will be equally binding upon [them]’.Footnote ¹⁴³ Alternatively, under Article 62(1) of the Statute, a state may request permission to intervene on the ground that it has ‘an interest of a legal nature which may be affected by the decision’. In this latter context, the question arises whether the Court’s conferral of locus standi on states other than an injured state to institute proceedings for the enforcement of an obligation erga omnes logically requires that it permit, on the same basis, the intervention in the proceedings of all other states having a legal interest in the matter. Put differently, where the breach of an obligation erga omnes is at issue, there appears to be no distinction between the interest of the state instituting the proceedings and the interests of states seeking to intervene under Article 62(1).Footnote ¹⁴⁴ As such, the intervention in the proceedings of all states to which the obligation erga omnes is owed must be permitted, since ‘[w]hatever “interest of a legal nature” is required in Article 62 of the Statute, it cannot be higher than the one that justifies bringing a claim before the Court’.Footnote ¹⁴⁵ This permissive approach to intervention under Article 62 has the advantage of discouraging a multiplicity of proceedings pertaining to the same breach. In light of an anticipated increase in what has so far been a limited interest in intervention, however, considerations of judicial economyFootnote ¹⁴⁶ may warrant the revision of the Court’s existing procedures for intervention under the Statute.Footnote ¹⁴⁷

3.5 Broader considerations

In addition to the issues discussed, the conferral by the Court of locus standi to institute proceedings for the enforcement of obligations erga omnes poses the broader question as to how to strike ‘[the] appropriate balance between the collective interest in compliance with basic community values and the countervailing interest in not encouraging the proliferation of disputes’.Footnote ¹⁴⁸ Those who are reluctant to confer a right of standing for the enforcement of obligations erga omnes are concerned not only about an increase in inter-state adjudication but also the corresponding use and misuse of unilateral countermeasures, ostensibly in the collective interest.Footnote ¹⁴⁹ It is also sometimes suggested, including by some judges at the Court, that non-adjudicatory means of dispute resolution are preferable.Footnote ¹⁵⁰ Conversely, the sufficiency of non-adjudicatory measures to strike this balance, including within the framework of the UN, remains contested, and ignores the important contribution of the ICJ in the settlement of international disputes.Footnote ¹⁵¹ When it comes to countermeasures, moreover, there is considerable support for the view that the availability of adjudication is likely to reduce resort to countermeasures,Footnote ¹⁵² with one commentator suggesting that the risk of litigation incentivizes greater compliance with obligations erga omnes ab initio.Footnote ¹⁵³

On balance, the anticipated increase in the adjudication of disputes as a justification to limit standing for the enforcement of obligations erga omnes is overstated. To begin with, many multilateral treaties explicitly provide for a right of standing in the collective interest.Footnote ¹⁵⁴ The practical effects of the conferral by the Court of a generalized right of standing to institute proceedings for the enforcement of obligations erga omnes is thus limited to ‘a narrowly defined circle of community interests’.Footnote ¹⁵⁵ What is more, a state’s decision whether to bring a dispute before the ICJ is a pragmatic one in which ‘the odds are weighted against a decision in favour of litigation’,Footnote ¹⁵⁶ and which may be co-ordinated among states,Footnote ¹⁵⁷ as in Rohingya Genocide. As one commentator observes, therefore, what is likely to be a relatively limited increase in adjudication before the Court may be a reasonable compromise for the enforcement of collective interests:

What is nevertheless clear is that the ‘teething problems’Footnote ¹⁵⁹ associated with identifying the various limits and consequences of the Court’s conferral of locus standi for the enforcement of obligations erga omnes require further detailed reflection.