Article 63 Intervention Before the International Court of Justice: New Developments and the Way Forward

[Ton Nu Thanh Binh is an LLM student at Trinity College Dublin and a recipient of the Ireland Fellows Programme]

The opinions expressed in this post are the author’s own and do not reflect the views of any institution the author might be affiliated with.

On 28 June 2024, Spain became the sixth country to submit a declaration to intervene in the case between South Africa and Israel before the International Court of Justice (ICJ). Previously, seven states intervened in The Gambia v Myanmar, and 32 states intervened in the Ukraine v Russia case under the 1948 Genocide Convention. This unprecedented development of ‘mass intervention’, where states take advantage of the right to intervene to make arguments in favour of one party in the case, raises two timely questions: what impact it has on the equality of the parties and how the ICJ should react to it.

This post argues that the ICJ failed to adequately balance the right to intervene under Article 63 of the Statute with the equality of the parties in the case of Ukraine v Russia. In addition, the Court’s recent amendments to its Rules regarding intervention were a timely response to the new development of Article 63 intervention but insufficient to address the impact that intervention may exert on the parties’ equality.

Overview of Article 63 Intervention 

Pursuant to Article 63 of the ICJ Statute, states that are parties to a convention have the right to intervene in proceedings that concern the construction of that convention. Under Article 84(1) of the Rules of Court, the Court must determine that these conditions are met.

ICJ judges have addressed the role of Article 63 intervention in past cases. Judge Weeramantry noted that intervention in domestic and international proceedings had two functions: to avoid repetitive litigation and to achieve harmony of principle. Judge Cançado Trindade viewed the role of intervention under Article 63 as ‘[contributing] to the progressive development of international law itself, especially when matters of collective or common interest and collective guarantee are at stake.’ Scholars such as Miron and Chinkin argued that Article 63, by engaging broader state participation in the act of interpretation, acknowledges the ‘res interpretata effect’ of the Court’s judgments, and other scholars – as elucidated by McIntyre – have explained how intervention might expand their ‘normative legitimacy’. From the intervenor’s perspective, Article 63 protects their right to be heard. Since all parties to a treaty have an interest in its construction, they should be allowed to express their version of interpretation to the Court before the Court gives decision on the matter, even if that interpretation would not be binding on states that are not parties to the case or have not, indeed, intervened under Article 63. In practice, how the ICJ interprets a multilateral treaty affects the legal interests of all state parties. 

Intervention in Ukraine v Russia 

Despite the perceived objectives of intervention under Article 63, states have recently intervened to show political support for one party. The Ukraine v Russia case was a typical example. During the written proceedings, at least nine states (Ireland, Spain, Latvia, Malta, Poland, Slovakia, Slovenia, Sweden and Estonia) accused Russia of failing to comply with the provisional measures order of the Court by expanding its military operations in Ukraine and aggravating the dispute. Norway explicitly ‘condemn[ed]’ the ‘war of aggression’ against Ukraine, calling it a ‘blatant violation of international law’ (para 16). Lithuania, New Zealand, and Poland made similar statements regarding the alleged use of force by the Russian Federation. France, Romania, the United Kingdom, Germany and Finland referred to the principle of good faith under international law. Germany submitted arguments about the Respondent’s ‘serious misuses of the Genocide Convention’ and ‘abuse of the law’ (paras 40, 45). In the hearing dated 20 September 2023, although the Court allocated only 10 minutes for each party’s submission on the subject matter of their intervention and 15 minutes for joint oral observations (compared to 1.5 hours granted to New Zealand in the Whaling case), New Zealand, the UK and Slovenia continued to expressly support Ukraine’s submissions.

Russia argued that the declarations of intervention should be found inadmissible as they put the respondent in a seriously disadvantaged position where it would have to respond not only to the arguments advanced by Ukraine but also to those of the 33 intervening states acting as de facto co-applicants. The Court relied on its judgment in the Whaling case (which had involved only one intervening party) and dismissed this argument. It simply ruled that because intervenors under Article 63 did not acquire party status and were not allowed to deal with any aspect other than the construction of the convention, admitting the declarations of intervention would not affect the equality of the parties (paras 49, 53).

The Court’s reasoning raised at least two problems. Firstly, the declarations clearly went beyond the construction of the Convention stipulated under Article 63. As pointed out in the individual opinions of Judge Xue and Vice-President Gevorgian, the object of the intervention was not only about the construction of the Convention in accordance with Article 63 but to act as de facto co-applicants, arguing that the Respondent’s allegation of genocide was unfounded and that it violated the Genocide Convention. This type of intervention did not serve the purpose of Article 63 intervention. Admitting these declarations despite their excessive scope will open the door for future abuse of Article 63.

Secondly, the declarations threatened to compromise the equality of the parties and the good administration of justice. Although the ICJ affirmed that it would not consider any arguments, evidence, facts or rules of international law outside the Genocide Convention (para 84), one could not have failed to recognise the political pressure that 33 intervening declarations imposed upon the Court and the respondent. The fact that all of the intervening states expressed support for one side, and that their statements were made publicly available and attracted media attention, threatened to exert a significant amount of pressure on judges in deciding the case. 

As for Russia, since it had to respond to many overlapping arguments, including some outside the scope of Article 63, it risked being subject to the undue pressure created by intervention. One may argue that responding to largely identical arguments does not necessarily create a huge additional burden, and both Ukraine and Russia had to respond, after all. Nonetheless, there were slight variations among the declarations that Russia had to address. In its written observations dated 17 October 2022, 15 November 2022, 16 December 2022 and 30 January 2023, Russia demonstrated how each declaration sought to address issues unrelated to the construction of the Genocide Convention. On the other hand, Ukraine’s views on all declarations were the same – arguing that they were admissible in meeting the conditions under Articles 63 and 82 of the ICJ Statute. This extra work burdened upon Russia proves that intervention may infringe on the equality of the parties.

The Updated Rules of the Court 

On 28 February 2024, the Court announced significant amendments to its Rules relating to intervention, which entered into force on 1 June 2024. Juliette McIntyre viewed this as an attempt to save the Court from another Ukraine v Russia scenario. Article 82 of the Rules sets clear time limits for filing a declaration of intervention. Article 63 interventions must now be filed before the deadline for the Counter-Memorial. It used to be ‘the date fixed for the opening of the oral proceedings’. It seems evident that this change aims to prevent the third party from disrupting the proceedings with a last-minute declaration of intervention. 

The second important amendment is Article 86(2), which retains the Court’s discretion in deciding whether to allow the intervening state under Article 63 to join the oral proceedings. Under the previous Rules, the intervening state ‘shall be entitled, in the course of the oral proceedings, to submit its observations’. The wording has been changed to ‘may also submit its observations’, followed by an exception at the end of the provision: ‘unless the Court decides otherwise’. The right to intervene under Article 63 thus no longer guarantees participation in the hearings. Oral pleadings before the World Court are where intervening states can show their ‘solidarity act’ to the public and media. When participation in the hearings is no longer guaranteed, states may reconsider their intention to intervene.

Overall, the amendments to Article 82 and Article 86(2) are a commendable attempt to prevent the interference that intervention may impose upon the proceedings, particularly the type of intervention used as ‘co-operative condemnation’ in Ukraine v Russia. However, Article 86 of the Court’s Rules provides no criteria for the ICJ to consider whether to allow the intervening state to participate in the hearing. Neither does it help relieve the potential burden on the main parties to respond to a plethora of arguments from a significant number of intervening states. Given this fact, the amended rules may not be as effective as it first seemed.  

Recommendations for the ICJ

In the context of a resurgence of intervention based on community interests, a timely question for the ICJ is how to balance the right to intervene under Article 63 and its possible adverse impact upon the parties and the proceedings. 

In this regard, European Court of Human Rights (ECtHR) practice may provide helpful guidance. In parallel with the ICJ genocide case, the ECtHR received requests to intervene from 26 member states in the case concerning the military operations in Ukraine since 2022 and the conflict in eastern Ukraine in 2014. Facing this unprecedented wave of intervention, the ECtHR published a Practice Direction and announced amendments to the Rules of Court on third-party intervention (see the briefing here).

It is important to note that, compared to the ICJ, the ECtHR adopts a much more stringent approach in allowing intervention. Under Article 36(2) of the ECHR, third-party intervention before the ECtHR is not construed as a ‘right’ and is permitted only ‘in the interest of the proper administration of justice’. Nevertheless, the object of intervention under Article 36(2) of the ECHR is similar to intervention under Article 63 of the ICJ Statute. The ECtHR explains in its Practice Direction that since its judgments ‘elucidate and develop the rules laid down in the Convention and the Protocols thereto’, state parties to the ECHR have a ‘legitimate interest’ in submitting their views about a legal issue arising in a case before the Court (para 8). Informing the Court about a party’s construction of a convention is also the rationale behind intervention under Article 63 of the ICJ Statute.

The amended Rules of the ECtHR required the submission of a separate request to intervene in the hearings (Rule 44). The Practice Direction stipulates that intervening parties are not entitled to support one disputing party expressly (para 2). Moreover, a request for leave to intervene under Article 36(2) of the European Convention on Human Rights (ECHR) or Article 3, second sentence, of Protocol No. 16 must include information about, among other things, the reasons for intervention, the third party’s special knowledge about the issues arising in the case, the reasons why its submissions will be useful to the Court and differ from those of the parties or other third parties, and whether the third party proposes to make written comments, to participate in a hearing, or both (para 27). These details enable the ECtHR to assess whether it would be ‘in the interests of the proper administration of justice’ to allow the intervention.

While there are important structural differences between the Strasbourg Court and the ICJ, the ECtHR practice offers the latter a useful model to consider. The ICJ should clarify in its Rules the conditions for the admissibility of intervention and participation in the hearing. Firstly, Article 82 of the ICJ Rules should specify that the subject matter of the intervention must be limited to the construction of the treaty in question. This is not a new requirement, as the Court already ruled in the Whaling case (para 18). However, it should become a formal condition for intervention, the failure of which may result in the Court denying the intervenor’s participation in the hearing or, to a more serious extent, the inadmissibility of the declaration to intervene. 

Secondly, Article 82 of the ICJ Rules may add the following as optional information in declarations of intervention: (i) the intervening state’s special experience in the application of the convention, if any, and (ii) how its submissions will be useful to the Court and differ from those of the other parties. Given that participation in the hearing will no longer be an unconditional right, the declaration of intervention should also indicate whether the intervenor wishes to participate in the oral proceedings and the reasons for such a petition. This will encourage the potential intervenors to provide neutral and genuine observations regarding the construction of a convention rather than merely reiterate the arguments of the existing parties. For example, in the Whaling case, New Zealand brought in perspectives different from the disputing parties concerning the interpretation of the 1928 International Convention for the Regulation of Whaling, which the Court took seriously and ultimately drew upon in its judgment. This type of intervention is helpful for the Court in deciding a case and should be encouraged. By contrast, interventions that primarily seek to express political support for a party to the case, rather than illuminate alternative constructions of the treaty in question, should not be encouraged. 

Conclusion

The renewed interest in intervention may signal confidence in the role of international tribunals in protecting humanitarian values. However, the intervention that collectively condemns one party goes beyond its intended purpose and risks compromising the fair administration of justice. The mass intervention in Ukraine v Russia not only raised concerns about such problems but also does not appear to have helped Ukraine, since the Court rejected Ukraine’s arguments on jurisdiction and severely limited the scope of the case going forward. Moreover, the Court’s recent amendments to its Rules have had limited effect in preventing a similar scenario from happening again. Drawing from the practice of the ECtHR, this post suggests that the ICJ further amend its Rules with clarified conditions for the admissibility of intervention and the participation of intervening states in the hearing. This will encourage genuine intervention under Article 63 of the ICJ Statute while discouraging the types of third-party participation that are likely to affect the fair administration of justice.

The author is greatly thankful to Professor Michael A Becker, Assistant Professor of International Human Rights Law at Trinity College Dublin, for his invaluable comments and review of this piece.