On 5 March 2025, Sudan instituted proceedings against the United Arab Emirates (UAE) before the International Court of Justice (ICJ) regarding alleged violations by the UAE of its obligations under the Convention on the Prevention and Punishment of Genocide (the Genocide Convention). The case concerns allegations that the UAE is supporting Sudan’s paramilitary Rapid Support Forces against the Masalit group in West Darfur.
A significant question is whether the ICJ has jurisdiction over the dispute. The UAE has a reservation to Article IX of the Genocide Convention, its compromissory clause. To seize the ICJ of jurisdiction, Sudan suggests that the UAE’s reservation to Article IX is invalid as it is against the object and purpose of the Genocide Convention. Given this position, for good reason, the immediate preoccupation of academic thought is likely to judge the merits (or lack thereof) of Sudan’s position on the UAE’s reservation.
Practically, this issue is a fait accompli. In 1951, the ICJ confirmed that reservations to the Genocide Convention are permissible (Reservations to the Genocide Convention, p. 24). In 1999, the ICJ determined that reservations to Article IX by the United States and Spain meant that it could not exercise “even prima facie” jurisdiction in respect of those States (Legality of Use of Force (United States), para. 25; Legality of Use of Force (Spain), para. 35). In 2006, in Armed Activities, the ICJ rejected the Democratic Republic of Congo’s challenge to Rwanda’s reservation to Article IX on the ground that it was “incompatible with the object and purpose” of the Genocide Convention (paras 57, 67-70).
Perhaps a more interesting question raised by Sudan’s claim is the permissibility of interventions by States-party to the Genocide Convention.
The proceedings instituted by Sudan are the latest in the spate of cases brought under the Genocide Convention in recent years. Each of these cases had an unprecedented number of interventions filed pursuant to Article 63 of the ICJ Statute by the States-parties to the Genocide Convention. Illustratively, in Gambia v. Myanmar, 11 States; in Ukraine v. Russia, over 30 States; and in South Africa v. Israel, 12 States have filed declarations of intervention. With the latest Genocide Convention case having been commenced, States-party to the Convention will again consider the value to intervene.
In principle, Article 63 provides every State party to a convention under consideration in proceedings before the ICJ to intervene to present its construction of the convention. An intervention under Article 63 provides the ICJ with a limited margin of appreciation for assessing the admissibility of the declaration and is described as an “intervention as of right” (Whaling in the Antarctic, Declaration by New Zealand, Sep. Op. of Judge Trindade, para. 24).
However, the ICJ’s Order on the Admissibility of the Declarations in Ukraine v. Russia complicates this “right”. The United States, with a reservation to Article IX, attempted to avail itself of the right to intervene as a State party to the Genocide Convention conferred upon it by Article 63 of the ICJ Statute.
The ICJ unanimously determined that the United States could not intervene in the proceedings “in relation to the construction of Article IX of the Convention while it is not bound by that provision” (Order on Admissibility (Ukraine v. Russia), para. 95). The ICJ emphasised that Article 63 “permits States parties to a convention to intervene in relation to the construction of any provision in question before the Court, provided that they are bound by the provision in question” (Order on Admissibility (Ukraine v. Russia), para. 96, emphasis added).
This ruling appears to import a condition into Article 63 that is absent from its wording. Article 63 is unqualified, obligating the Registrar to notify “all” States parties to the convention under consideration. Pursuant to Article 63(2), “[e]very State so notified has the right to intervene”.
The ruling has an inherent tension with the ICJ’s previous rulings in respect of the Genocide Convention as to who is a considered a State party to the Genocide Convention. In the Advisory Opinion on the Reservations to the Genocide Convention, the first question before the ICJ was whether a reserving State to the Genocide Convention can be regarded as being a party to it (p. 21). The ICJ answered that if a reservation is compatible with the object and purpose of the Genocide Convention, a reserving State can be regarded as being a party (p. 29). A reservation to Article IX has already been determined to be in accordance with the object and purpose of the Convention in Armed Activities (para. 70), which has implicitly been reiterated in the Order in Ukraine v. Russia (para. 94). In the circumstances, once it is apparent that a State is party to the relevant treaty, “it is not for the Court to grant or withhold permission” (Nicaragua v. United States, Sep. Op. of Judges Ruda, Mosler, Ago, Jennings and Lacharriè, para. 1).
Despite these peculiarities, the recency and unanimity of the ruling make it unlikely that the ICJ would change course. Nevertheless, the extension of this principle creates an absurd position in the context of Sudan v. UAE. There are fifteen States (besides the UAE) that have a reservation to Article IX. Yet, if the ICJ’s Order in Ukraine v. Russia were to apply, none of these States would have a right to intervene pursuant to Article 63 of the ICJ Statute, despite being squarely impacted by Sudan’s proposition that reservations to Article IX are invalid in light of the object and purpose of the Genocide Convention.
A potential solution for these fifteen States is to have recourse to Article 62 of the ICJ Statute. Article 62’s “raison d’etre…is to enable a third State, whose legal interest might be affected by a potential decision of the Court, to participate in the main case in order to protect that interest” (Territorial and Maritime Dispute, Judgment on the Application by Honduras, para. 46). Across the three other recent cases involving the Genocide Convention, only one State (i.e., Nicaragua in South Africa v. Israel) has taken recourse to this provision. This is unsurprising given that the ICJ enjoys a wider margin of appreciation to admit Article 62 interventions in comparison to that for Article 63.
The primary substantive requirement for a reserving State to intervene in the proceedings is to show the existence of a legal nature that may be affected by the decision. The ICJ has defined this aspect negatively as an interest “based on law, as opposed to a claim that is purely political, economic or strategic in nature” (Territorial and Maritime Dispute, Judgement on the Application by Costa Rica, para. 26). On the face of it, a reserving State should not have any issues in fulfilling this requirement. However, the Order in Ukraine v. Russia determined that the United States, having reserved Article IX had no “legal interest” in respect of the interpretation of the provision (para. 95). This must be distinguishable in Sudan v. UAE.
Even if it were assumed that a reserving State does not have a legal interest for a general interpretation of Article IX, the State would surely have a legal interest in protecting the validity of its reservation thereto. In any event, in Gambia v. Myanmar, the ICJ, having taken note of the obligations in the Genocide Convention being erga omnes partes, concluded that “each State party has an interest in compliance with them in any given case” (at para. 107).
Another potential hurdle to the utilisation of Article 62 is the need to show that the specific interest of the intervening State may be affected by the proceedings at hand. Relying on the Advisory Opinion on the Reservations to the Genocide Convention, the ICJ may take the position that in Sudan v. UAE, it is evaluating the UAE’s reservation individually, such that the intervening State requires no further protection that is not already provided by Article 59 of the ICJ Statute. However, such an interpretation would fall foul of the purpose of Article 62. Indeed, as noted by Judges Trindade and Yusuf, reliance on Article 59 deprives States from informing the Court of its interest before the main decision, as Article 62 specifically contemplates the involvement of third-parties in light of the “ever-increasing complexity and multilaterization of international relations” (Territorial and Maritime Dispute, Judgement on the Application by Costa Rica, Diss. Op. of Judges Trindade and Yusuf, paras 26-27).
Despite these complications, there remains a strong value for States to intervene in proceedings involving multilateral conventions of widespread importance. Indeed, even if a State has intervened unsuccessfully, it is likely to have alerted the ICJ to its interests, which may be sufficient in and of itself. If nothing else, it provides the ICJ with a further opportunity to build on its, for the time being, thin jurisprudence in respect of the viability of interventions under Articles 62 and 63 of the ICJ Statute.
