Mass Intervention?: The Joint Statement of 41 States on Ukraine v. Russia

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On 20 May 2022, 41 states and the EU issued a Joint Statement regarding the pending ICJ proceedings in Ukraine v. Russia. The Joint Statement indicates that the signatories agree “to explore all options to support Ukraine in its efforts before the ICJ and to consider a possible intervention in these proceedings”. One of the signatories, Romania, had days earlier indicated its intent to intervene. President Zelenskyy has characterized these developments as follows:

42 states took Ukraine’s side in the case against Russia at the International Court of Justice and intend to join the proceedings. Grateful to partners who chose the right side of history. The side of truth, international law, and justice. Together, we’ll hold Russia accountable.

The present post briefly compartmentalizes key questions raised by the Joint Statement. These questions are further explored in the author’s forthcoming Cambridge University Press monograph, Intervening in International Justice: Third States Before Courts and Tribunals.

Forms of Intervention

Although the ICJ routinely receives submissions from many states during its advisory proceedings, mass participation is unprecedented in the Court’s contentious cases. Romania, the state which has thus far set out the clearest intent to intervene in the present case, is uniquely familiar with this distinction. In the early days of the PCIJ, Romania requested “to intervene” in the Acquisition of Polish Nationality advisory proceedings. The Court responded that the general right of states to be heard in advisory proceedings reflects a fundamentally different procedure than intervention in contentious cases [220].

Article 62 of the ICJ Statute provides that a state may request to intervene in a contentious case if it “consider[s] that it has an interest of a legal nature which may be affected by the decision in the case”. The Court has further perplexed Article 62 intervention by construing this mechanism as itself providing two distinct channels of participation. A state may intervene as a non-party (i.e., as a guest making written and oral submissions on a circumscribed set of issues) by meeting the express requirements of Article 62. However, if it does so with a jurisdictional link to the parties—encompassing the subject-matter of the case—it can intervene as a full party in its own right (this has never occurred).

Article 63 appears to confer upon the contracting states of any convention a more definitive “right to intervene” as a non-party whenever that treaty’s “construction […] is in question”. As with Article 62, this provision was modelled closely on the corresponding article of the PCIJ Statute.

As a non-state, the EU is not entitled to request or declare intervention in contentious cases before the Court. Among the other 41 signatories to the Joint Statement, three are not parties to the Genocide Convention (Japan, Marshall Islands, Micronesia). As Ukraine’s application in this case refers to the Convention as the sole source of applicable law in this case, those three states cannot intervene under Article 63 of the Statute. The remaining 38 signatories may file interventions under Article 63 in principle, though the scope of such intervention remains limited to questions of treaty interpretation.

Article 62 Interests

Intervention under the broader rubric of Article 62 raises particularly thorny questions in this case. As a threshold matter, the Court has not clarified whether an interest in the fulfilment of an obligation erga omnes constitutes an “interest of a legal nature which may be affected by the decision” of the Court.

The present author considers that obligations erga omnes do not meet this threshold. The purpose of rules concerning the invocation of state responsibility is arguably satisfied once a state brings a justiciable action. This objective is not necessarily furthered by adding more states to ongoing proceedings. Nor is there a clear basis to analogize between customary requirements for the admissibility of applications instituting proceedings and statutory requirements for the admissibility of ‘incidental proceedings’ [sec. D], such as non-party intervention.

Even if the Court were to admit Article 62 intervention on this basis as a general matter, this premise is further complicated by the novelty of the present case, in which Ukraine requests the Court to find that Ukraine itself has not breached the Genocide Convention. Here, the question is not whether states have an Article 62 “interest” in seeking accountability for breaches of obligations erga omnes, but rather whether they have such an interest in refuting the existence of these breaches.

Some of the Joint Statement’s signatories may consider instead basing Article 62 intervention on a more direct interest, arising from the immigration of Ukrainian refugees to their territories. However, the question remains as to whether such interest “may be affected by the decision” in this particular case. The diaspora arguably lacks a proximate connection to Ukraine’s claim that it has not committed genocide. This causal element of Article 62 would be more clearly satisfied if Ukraine further claimed in its application instituting proceedings (or a subsequent amendment thereto) that it is Russia which has undertaken a genocidal campaign.

Timing and Framing

The Court has shown great reluctance to admit intervention under Article 62 or 63 while questions of jurisdiction and admissibility remain pending. In this respect, the Court emphasizes the ‘incidental’ character of non-party intervention more vigilantly than in other incidental proceedings (such as provisional measures, where jurisdiction is assessed solely on a prima facie basis). In cases such as Nuclear Tests and Nicaragua, the Court deferred and ultimately dismissed such interventions without consideration. It is thus unsurprising that Maldives, Canada and the Netherlands have not intervened while preliminary objections remain pending in The Gambia v. Myanmar, despite having expressed their intent to do so in 2020.

Because Russia is not formally participating in the present case, the Court has not bifurcated the proceedings into separate phases on jurisdiction and the merits. This is potentially problematic for the prospect of intervention. If questions of jurisdiction or admissibility remain pending until the Court renders its sole Judgment in the case, then hewing to its practice would effectively foreclose intervention.

It is possible that the Court would treat this question differently if a contracting party to the Genocide Convention were to request to intervene as a full party under Article 62, given the seemingly non-incidental character of party-based intervention. An alternative way to transcend the Court’s rationale for deferring interventions may be to frame the Article 62 application or Article 63 declaration as confined exclusively to questions of a jurisdictional nature. Indeed, the Joint Statement appears to hint at this latter approach (“We strongly believe that this is a matter rightfully brought to the ICJ”).

This may be an appropriate case for testing that approach, given Ukraine’s novel application of the Genocide Convention, and the skepticism which some ICJ judges have voiced concerning its jurisdiction in this case. However, it is not clear that governments wish to intervene just to argue questions that only a lawyer could love, divorced from the toll and depravity of Russia’s war against Ukraine.

The Limits of Solidarity

It may be assumed that a “joint intention” to intervene does not suggest a single filing credited to multiple signatories. Such a prospect was unforeseen in 1920, when articles 62 and 63 were originally drafted. The admissibility of such intervention has remained untested, and would appear to be unmanageable, unless certain signatories were to lead by pleading on their joint behalf. Thus when five states sought to intervene in the days following the institution of Request for Examination, they did so in five separate filings, despite evident collaboration.

Certain additional questions may attach to Article 62 applications in this case. Under Article 81 of the ICJ Rules of Court, such applications must state the “precise object of the intervention”. While the Court has not been forthright on this point, its practice suggests that such object must be to inform the Court of the third state’s uniquely held legal interests. It has not characterized intervention in the sense of ‘taking sides’, as President Zelenskyy frames it. It is thus entirely possible that the solidarity expressed in the Joint Statement ensures that none of its signatories meet this threshold.

If applying to intervene under Article 62 as a full party, a related question would arise under Article 31(5) of the Statute, which codifies the doctrine of ‘parties in the same interest’. This does not factor into the Court’s decision whether to admit intervention as a party, but would likely foreclose the possibility of any such states appointing judges ad hoc in this case. The ICJ would certainly balk at the prospect of quadrupling the size of its bench in any given proceeding.

Concluding Observation

A single intervention can add months or even years to the life of a case—perhaps longer when intervening as a full party under Article 62. In this light, the Joint Statement promises to exponentially slow the accountability which its signatories are seeking. In the specific circumstances of this case, it is thus worth considering whether these states could more effectively contribute by collaborating with Ukraine ‘behind the scenes’. In contrast to intervening, marshaling resources to directly assist a litigant state with legal and factual questions has raised few concerns in ICJ practice. Those signatories which support Kyiv militarily and economically can similarly add their legal support without declaring it from a lectern in The Hague.

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Nicolas Boeglin says

May 30, 2022

Dear Professor McGarry

Many thanks for this extremely complete post. If I not wrong, France was the very first State annoncing its intention to support Ukraine before ICJ.

I refer you and our colleagues to French MFA´s declaration of March 17th, 2022, available at

in which it can be read that:

"Comme l’y autorise le Statut de la Cour internationale de Justice, la France se tient prête à intervenir dans cette procédure, au soutien de l’Ukraine, car cette affaire concerne également nos intérêts fondamentaux pour le plein respect du droit international".

I refer you to to a brief note I wrote of ICJ´s order of March 16th, available at:

Yours sincerely

Nicolas Boeglin

Brian McGarry says

May 31, 2022

Dear Prof. Boeglin,

Thank you for your comment, and for bringing France's March 2022 statement to my attention. Now let's see what comes of it...

Best regards,