Belize v Honduras: Guatemala Intervening

1. Case Details

Belize v. Honduras (Sovereignty over the Sapodilla Cayes/Cayos Zapotillos), Application by the Republic of Guatemala for Permission to Intervene.[1]

Court:International Court of Justice, The Hague.

Date of decision:19 March 2026.

Bench composition: President Iwasawa; Vice-President Sebutinde; Judges Tomka, Abraham, Xue, Bhandari, Nolte, Charlesworth, Brant, Gómez Robledo, Cleveland, Aurescu, Tladi, Hmoud and Okowa; Registrar Gautier (fifteen-member Bench; decision unanimous).

2. Introduction

Intervention by third States remains one of the least used and most contested procedures before the International Court of Justice. This judgment, delivered in the territorial dispute between Belize and Honduras over the Sapodilla Cayes, is significant because the Court granted Guatemala permission to intervene, something it has done only rarely in its history[2]. Two features make the decision noteworthy. First, the Court clarified what a third State must show to establish an “interest of a legal nature” under Article 62 of the Statute, drawing a careful line between an interest and a right[3]. Second, and more strikingly, the Court held that once the statutory conditions are satisfied, it has no residual discretion to refuse intervention, rejecting Honduras’s abuse-of-process objection outright[4]. The judgment therefore reshapes the procedural landscape for third States whose claims overlap with disputes already before the Court.

3. Facts of the Case

The story behind this case begins in the Gulf of Honduras, a stretch of Caribbean coastline shared by three neighbours: Belize, Guatemala, and Honduras. Tucked within this gulf lies a small cluster of maritime features called the Sapodilla Cayes, though Honduras knows them by a different name: the “Cayos Zapotillos.” Sitting some 20 to 25 nautical miles from all three coastlines, these cays have long been a quiet but persistent source of tension in the region, with more than one country insisting they belong to them.

Belize decided to bring the matter before the International Court of Justice, filing an Application against Honduras on 16 November 2022. Belize’s case rests on a narrative of inherited authority: it argues that the United Kingdom governed the cays openly, peacefully, and continuously for many years, that Honduras never seriously contested this at the time, and that when Belize gained independence, it stepped into the UK’s shoes as the rightful sovereign. To bring this claim before the Court, Belize relied on Article XXXI of the 1948 American Treaty on Pacific Settlement, better known as the “Pact of Bogotá.”

Honduras, unsurprisingly, tells a very different story. It traces its claim back to Spain, arguing that sovereignty passed to Honduras upon independence, and points to a long history of governance and administrative acts, both by Spain and later by Honduras itself, as proof of its title over the cays.

Here is where things get more complicated. Belize and Honduras are not the only two players with a claim to this territory, Guatemala has been quietly asserting its own rights over the same cays for a long time. In fact, years before Belize ever filed against Honduras, Guatemala and Belize had already taken their own overlapping dispute to the Court. Back on 7 June 2019, the two countries jointly submitted a case titled “Guatemala’s Territorial, Insular and Maritime Claim (Guatemala/Belize)”, in which both sides claim sovereignty over these very same cays. Guatemala’s claim, much like Honduras’s, is rooted in the idea that it inherited Spanish title after independence.

So, by the time Belize brought its case against Honduras, there were already two separate but closely intertwined disputes sitting before the same Court, both circling the same piece of territory. It’s this overlap that pushed Guatemala to act. On 1 December 2023, Guatemala filed an application asking the Court for permission to intervene in the Belize-Honduras case, invoking Article 62 of the Court’s Statute. Guatemala’s worry was simple and understandable: whatever the Court decided about sovereignty in the Belize-Honduras dispute could end up shaping, or even undermining, the very claim Guatemala was pursuing separately against Belize over the identical territory.

Interestingly, the two original parties didn’t see eye to eye on this request. Belize had no objection to Guatemala joining the proceedings, but Honduras pushed back, opposing the intervention outright. This disagreement is what eventually brought the matter to public hearings, held over three days on 24, 25, and 26 November 2025, where the Court had to work out whether Guatemala had genuinely satisfied the legal requirements needed to step into a case it wasn’t originally part of.

4. Legal Issues

Since this phase of the case dealt exclusively with Guatemala’s request to intervene, the legal issues before the Court weren’t about who actually owns the Sapodilla Cayes/Cayos Zapotillos, that question remains for the merits stage. Instead, the Court had to work through the more technical, but no less important, framework governing third-party intervention under Article 62 of the Statute and Article 81 of the Rules of Court. Reading through the Judgment, the issues essentially break down as follows:

Issue 1: Whether Guatemala has demonstrated an “interest of a legal nature” which may be affected by the Court’s decision in the main proceedings between Belize and Honduras, as required under Article 62 of the Statute?

Issue 2: Whether Guatemala has sufficiently specified the “precise object” of its intervention, in accordance with Article 81, paragraph 2 (b), of the Rules of Court?

Issue 3: Whether Guatemala is seeking to intervene as a party or as a non-party to the proceedings, and, depending on that characterisation, whether a valid jurisdictional link exists between Guatemala and Honduras?

Issue 4: Whether Guatemala’s failure to attach a list of supporting documents to its Application is fatal to its request, given the requirements of Article 81 of the Rules of Court?

Issue 5: Whether, independently of the above, the Court retains discretion to reject Guatemala’s Application on the ground of an alleged “abuse of process,” as argued by Honduras?

5. Arguments Presented by the parties

Since this stage of the proceedings turned on Guatemala’s request to intervene rather than the underlying sovereignty dispute, the arguments here don’t split neatly along the usual Applicant/Respondent lines. Instead, the real contest was between Guatemala, pushing to be let into the case, and Honduras, resisting that move, with Belize occupying a more neutral, largely supportive position throughout.

5.1 Guatemala’s Arguments

Guatemala framed its case for intervention around a fairly intuitive concern: it has been asserting sovereignty over the Sapodilla Cayes/Cayos Zapotillos for a long time, and that claim is already the subject of a separate, ongoing case against Belize. Guatemala argued that:

Its interest in the cays is a genuine, longstanding legal claim, not some passing or generalised concern, and it is directly tied to the same territory at stake in the Belize-Honduras dispute

Any ruling the Court makes on sovereignty in the main case could realistically spill over and affect the position Guatemala is defending in its own parallel case against Belize

The two objects behind its request  protecting its legal interests and informing the Court of the nature and extent of its rights  are legitimate and well established in the Court’s own past practice on intervention

Since it lacks a jurisdictional link with Honduras, it should be understood as seeking to intervene as a non-party, a status that does not require such a link

Its failure to attach a list of supporting documents was not a procedural defect, since Article 81 only requires such a list where documents are actually annexed, which Guatemala chose not to do

5.2 Honduras’s Arguments

Honduras took a considerably more skeptical view of Guatemala’s request, resisting it on several fronts:

It argued that the object of Guatemala’s intervention was vague, imprecise, and, in its words, even “contrived,” falling short of the specificity required under Article 81, paragraph 2 (b), of the Rules of Court

It suggested that Guatemala already has an adequate forum to protect its interests, the separate Guatemala/Belize case making intervention in this proceeding unnecessary and duplicative

It raised the absence of a list of supporting documents as a procedural shortcoming in Guatemala’s Application

Most strikingly, Honduras argued that the Court possesses a general discretion to refuse intervention applications altogether, and that it should exercise that discretion here on the basis that Guatemala’s request amounted to an abuse of process

5.3 Belize’s Position

Belize did not object to Guatemala’s intervention as a matter of principle, though it did raise a practical question: given that Guatemala and Belize were already litigating the same sovereignty issue in their own case, what additional information could Guatemala realistically bring to this proceeding that hadn’t already been aired elsewhere? Belize’s position, then, was less an objection and more a mild note of curiosity about the practical value of the intervention.

6. Court’s Reasoning and Analysis

The Court treated Guatemala’s request as an application for intervention under Article 62 of the Statute, and it approached the matter in a careful, step-by-step way. It first examined whether Guatemala had shown an interest of a legal nature that could be affected by the judgment. The Court accepted that Guatemala’s claim was not abstract or political: it was a real and concrete claim to sovereignty over the Sapodilla Cayes/Cayos Zapotillos, and sovereignty is, by its nature, a legal question. The Court also noted that the main case would require it to decide sovereignty over the same maritime features, so the eventual judgment could directly affect Guatemala’s position in its parallel dispute with Belize. In that sense, the Court rejected the idea that Guatemala had to prove an actual legal right would certainly be harmed; it was enough that its legal interest may be affected.

The Court then turned to the precise object of the intervention. Guatemala had said that it wanted to protect its legal interests over the cays and to inform the Court of the nature and extent of those interests. The Court held that this was a proper and familiar purpose for intervention. It emphasised that Guatemala was not trying to introduce a new dispute or change the character of the case between Belize and Honduras. Instead, it sought only to ensure that its own position on sovereignty would be visible to the Court in proceedings where the same territory was in issue. The Court also rejected Honduras’s suggestion that Guatemala should be refused because it could make its case in the separate Belize/Guatemala proceedings. The Court made clear that the existence of another case does not remove a State’s right to seek intervention where the requirements of Article 62 are met.

A further issue concerned jurisdiction. The Court explained that a State may intervene either as a party or as a non-party, but an autonomous jurisdictional link is required only for intervention as a party. Since Guatemala had no such jurisdictional link with Honduras, the Court treated the application as one for intervention as a non-party It also dismissed Honduras’s objection based on the absence of a list of supporting documents, holding that the burden of proof lies with the intervening State and that the form of proof remains within its discretion.

Finally, the Court addressed Honduras’s argument that Guatemala’s request was an abuse of process. It refused to accept that objection, stating that its role was to assess objectively whether the legal conditions for intervention had been met, not to exercise a free-standing discretion to refuse a properly grounded application. Since those conditions were satisfied, the Court allowed the intervention, but only within a limited scope: sovereignty over the Sapodilla Cayes/Cayos Zapotillos, including the fishing rights in the surrounding waters[5].

7. Judgment and Ratio Decidendi

The Court unanimously held that Guatemala is permitted to intervene as a non-party in the case, but only to the extent and for the purposes set out in the judgment. Its intervention is limited to the issue of sovereignty over the Sapodilla Cayes/Cayos Zapotillos, including fishing rights in the waters surrounding them.

The ratio decidendi is that a State may be allowed to intervene under Article 62 of the Statute where it shows an interest of a legal nature that may be affected by the Court’s decision, and where the intervention has a precise object connected to the subject-matter of the dispute. The Court also confirmed that intervention may proceed as a non-party even where no autonomous jurisdictional basis exists between the intervening State and one of the parties to the main case.

8. Critical Evaluation

The Court’s decision is convincing because it applies Article 62 in a practical and careful way. It recognises that intervention is meant to protect a third State’s own legal interests without turning the case into a broader, unrelated dispute. By allowing Guatemala to intervene only on the limited question of sovereignty over the Sapodilla Cayes/Cayos Zapotillos, including fishing rights in the surrounding waters, the Court struck a balance between participation and judicial economy.[6]

The judgment is also important because it confirms that a State does not need to prove that its rights will certainly be harmed. It is enough to show that an interest of a legal nature may be affected by the Court’s decision. That approach preserves the practical value of intervention, especially in cases involving overlapping territorial claims. At the same time, the Court avoided opening the door to unlimited third-party participation by insisting that the object of intervention must remain tied to the subject-matter of the main dispute.[7]

One strength of the ruling is its rejection of Honduras’s abuse-of-process objection. The Court made clear that intervention is not a discretionary favour but a legal mechanism governed by objective conditions.[8] This gives the decision doctrinal clarity and reduces the risk of intervention being blocked for strategic reasons.

The judgment is less expansive, however, than a case on the merits. It does not decide sovereignty over the cays themselves, nor does it settle the competing territorial titles. Its significance lies instead in procedural law and in the Court’s interpretation of intervention under Article 62. For that reason, the case is best understood as strengthening the procedural rights of third States while preserving the bilateral structure of the main dispute.[9]

9. Conclusion

This case shows how the Court uses Article 62 of its Statute to protect the interests of a third State when those interests may be affected by a pending judgment. The decision does not resolve the underlying sovereignty dispute between Belize and Honduras, but it confirms that Guatemala has a sufficient legal interest to enter the proceedings in a limited capacity. In doing so, the Court kept the intervention tightly focused while recognising the practical reality of overlapping territorial claims.

More broadly, the judgment reinforces the idea that intervention is a procedural safeguard, not an exceptional favour. It allows the Court to hear from a State whose legal position could be touched by the outcome, without disturbing the structure of the main case. For that reason, the decision is an important example of how the Court balances fairness to third States with the need to preserve the integrity of the dispute before it.

10 Bibliography :-

10.1 Cases

Sovereignty over the Sapodilla Cayes/Cayos Zapotillos (Belize v Honduras: Guatemala intervening) (Judgment) 19 March 2026, ICJ General List No 185.

10.2  Provisions Referred

Statute of the ICJ

1. Article 59: The decision of the Court has no binding force except between the parties and in respect of that particular case.
2. Article 62: If a State considers that it has an interest of a legal nature which may be affected by the decision in the case, it may submit a request to the Court to be permitted to intervene.
3. Article 81: Sets out the requirements for an application for permission to intervene, including the interest claimed, the precise object of the intervention, and the jurisdictional basis relied on.
4. Article 85: If intervention is granted, the intervening State is supplied with the pleadings and documents and may file a written statement within the time-limit fixed by the Court.

Rules of Court

1. Article 81, paragraph 2(a): The application must specify the interest of a legal nature which the State applying to intervene considers may be affected by the decision in the case.
2. Article 81, paragraph 2(b): The application must set out the precise object of the intervention.
3. Article 81, paragraph 2(c): The application must indicate any basis of jurisdiction claimed to exist as between the State seeking to intervene and the parties to the case.
4. Article 81, paragraph 3: The application may also specify the basis on which the intervening State considers that intervention is admissible.
5. Article 85, paragraph 1: If the Court grants permission to intervene, the intervening State is entitled to submit a written statement within a time-limit fixed by the Court.

10.3 Books and chapters

1. Andreas Zimmermann, Christian Tomuschat and Karin Oellers-Frahm (eds), The Statute of the International Court of Justice: A Commentary (2nd edn, OUP 2012).
2. Christine Chinkin, ‘Article 62’ in Andreas Zimmermann, Christian Tomuschat and Karin Oellers-Frahm (eds), The Statute of the International Court of Justice: A Commentary (2nd edn, OUP 2012).

10.4 Journal articles

1. B Bonafé, ‘Interests of a Legal Nature Justifying Intervention before the ICJ’ (2012) 25 Leiden Journal of International Law 739.
2. A de Hoogh, ‘Intervention under Article 62 of the Statute and the Quest for Incidental Jurisdiction without the Consent of the Principal Parties’ (1993) 6 Leiden Journal of International Law 17.
3. D W Greig, ‘Third Party Rights and Intervention before the International Court’ (1992) 32 Virginia Journal of International Law 285.
4. C Chinkin, ‘Third Party Intervention before the International Court of Justice’ (1986) 80 American Journal of International Law 495.
5. T Licari, ‘Intervention under Article 62 of the Statute of the ICJ’ (1982) 8 Brooklyn Journal of International Law 267.
6. Third-party State Intervention in Disputes Before the International Court of Justice: A Reassessment of Articles 62 and 63 of the ICJ Statute (2020) 53 Comparative and International Law Journal of Southern Africa.

10.5 Online commentary

1. Oren Perez, ‘Beyond Bilateralism’ (Verfassungsblog, 20 March 2026).
2. Fritz Kainz, ‘The Persistent Absent Third Party Issue in the Sapodilla Cayes Case’ (EJIL: Talk!, 8 April 2026).
3. ‘Guatemala’s Successful Application for Intervention and the Ongoing Debate Between Article 59’s Importance and Irrelevance in Assessing Article 62 Intervention Requests’ (NYU Journal of International Law and Politics Blog, 2 July 2026).

[1] Judgment of 19 March 2026, I.C.J. General List No. 185.

[2] Sovereignty over the Sapodilla Cayes/Cayos Zapotillos (Belize v Honduras: Guatemala intervening) (Judgment) 19 March 2026, ICJ General List No 185. 

[3] International Court of Justice, Sovereignty over the Sapodilla Cayes/Cayos Zapotillos (Belize v Honduras), Summary 2026/1, 19 March 2026. 

[4] Oren Perez, ‘Beyond Bilateralism’ (Verfassungsblog, 20 March 2026) <https://verfassungsblog.de/guatemala-intervention-icj/> accessed 13 August 2026.

[5] Guatemala’s Successful Application for Intervention and the Ongoing Debate Between Article 59’s Importance and Irrelevance in Assessing Article 62 Intervention Requests’ (NYU Journal of International Law and Politics Blog, 2 July 2026) <https://nyujilp.org/guatemalas-successful-application-for-intervention-and-the-ongoing-debate-between-article-59s-importance-and-irrelevance-in-assessing-article-62-intervention-requests/> accessed 13 August 2026.

[6] Sovereignty over the Sapodilla Cayes/Cayos Zapotillos (Belize v Honduras: Guatemala intervening) (order) 19 March 2026, ICJ General List No 185.

[7] Oren Perez, ‘Beyond Bilateralism’ (Verfassungsblog, 20 March 2026)  accessed 11 August 2026.

[8] ‘Guatemala’s Successful Application for Intervention and the Ongoing Debate Between Article 59’s Importance and Irrelevance in Assessing Article 62 Intervention Requests’ (NYU Journal of International Law and Politics Blog, 2 July 2026)  accessed 13 August 2026.

[9] ‘After Intervention: The Persistent Absent Third Party Issue in the Sapodilla Cayes Case’ (EJIL: Talk!, 8 April 2026)  accessed 12 August 2026.