ICJ Jurisdiction and Chagos Archipelago Dispute

Andrew McCaffrey
Vol. 40 Associate Editor

In the midst of the Indian Ocean lies the Chagos Archipelago, a remote group of islands that is both a tropical paradise and a bastion of military might.  The islands of the Chagos Archipelago are currently the subject of debate at the ICJ.[1]  Specifically, the ICJ recently heard arguments regarding UN General Assembly Resolution 71-292.[2]  This resolution requested an advisory opinion as to (1) whether the 1968 decolonization of Mauritius by Britain was lawfully completed and (2) what the international law consequences of continued British administration of the Chagos Islands are, including consequences of Mauritius’ inability to resettle its nationals, especially those of Chagossian origin, on the Chagos Islands.[3]  In addition to these two questions posed by the General Assembly, the ICJ’s jurisdiction has come into dispute.[4]

Historical Background

The United Kingdom gained control of Mauritius, including the Chagos Archipelago, from France in 1814.[5]  The British administered the Chagos Archipelago as a lesser dependency of Mauritius until November 8, 1965, when the archipelago was detached from the colony of Mauritius.[6]  Mauritius argues that this detachment was agreed to under duress as a precondition for Mauritius gaining independence from the British.[7]

Of course, this argument raises the question of why the British would want to maintain control of a particular portion of a colony that was about to gain independence.  The reason was that the United States wanted the islands as a military base, and the United Kingdom obliged its transatlantic ally by offering control of the archipelago to the United States.[8]

Consequently, from 1968 to 1973, the entire population of the Chagos Archipelago was removed by force to create space for the still active US military base on the archipelago’s largest island, Diego Garcia.[9]

Arguments For and Against ICJ Jurisdiction

The United Kingdom argues that because the issue of sovereignty over the Chagos Islands is a bilateral dispute, the ICJ “should exercise its discretion so as to decline to answer the Request for reasons of judicial propriety.”[10]  To support its position, the UK first points to support it has from other countries including Australia, France, Israel, and the United States.[11]  In other words, rather than elaborating on the nebulous meaning of “judicial propriety,” the United Kingdom’s first method of bolstering its position is to point to allies who have supported its position, two of which are permanent members of the UN Security Council.  What this statement lacks in logical cogency, it makes up for in pragmatic realism.  That is, by reminding the ICJ that multiple P5 states back the UK’s argument, the UK is likely to influence the court’s final judgment, on both the merits and the jurisdictional issues.

The United Kingdom then makes an argument based on lack of consent.  Citing an ICJ advisory opinion from 1975, the United Kingdom argues that if the ICJ were to issue an opinion on the merits, the court would be “circumventing the principle that a State is not obliged to allow its disputes to be submitted to judicial settlement without its consent.”[12]

Mauritius grounds its argument that the ICJ should render an advisory opinion on the basis of Article 65(1) of the ICJ statute and Article 96 of the UN Charter.[13]  The former tells us that the ICJ “may give an advisory opinion on any legal question at the request of whatever body may be authorized by or in accordance with the Charter of the United Nations.”[14]  The latter provides that either the General Assembly or the Security Council may request advisory opinions from the ICJ.[15]  Mauritius further argues that, contrary to the position adopted by the UK, “[t]here is no ‘compelling reason’ for the Court to decline to exercise the advisory jurisdiction which the Charter and the Statute have conferred upon it, and, on this basis and in keeping with all relevant precedents, it should exercise that jurisdiction and render the opinion which the General Assembly has sought.”[16]

In sum, Mauritius argues in favor of ICJ jurisdiction on the basis of treaty texts, while the United Kingdom argues against the Court’s jurisdiction on the basis of lack of consent to what the United Kingdom characterizes as a bilateral dispute.

Application of Treaty Text to Resolve Jurisdictional Issue

Because General Assembly Resolution 71-292 was submitted according to rules spelled out by treaties, it is logical to apply the treaties’ texts to resolve any issues.  Accordingly, I apply the Vienna Convention on the Law of Treaties to the UN Charter and the ICJ Statute.

Importantly, both Mauritius and the United Kingdom are parties to the Vienna Convention on the Law of Treaties.[17]  Per the VCLT, treaties should “be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose.”[18]

Unfortunately, ordinary meaning does go far in resolving the jurisdictional dispute in this case.  Because the operative verb in both Article 65(1) of the ICJ statute and Article 96(1) of the UN Charter is “may,” one must turn to the object and purpose of the statutes.

The ICJ statue is silent in terms of having an express purpose.  The UN Charter, however, is not.  In addition to maintaining international peace and security, one of the express purposes of the UN Charter is “[t]o develop friendly relations among nations based on respect for the principle of equal rights and self-determination of peoples.”[19]  Because one of the underlying issues in the dispute over the Chagos Islands are the “consequences of Mauritius’ inability to resettle its nationals, especially those of Chagossian origin, on the Chagos Islands,”[20] a matter of self-determination is directly involved in the case.

The United Kingdom’s argument does not hold up.  Although consent to judgment is a traditional requisite for ICJ jurisdiction, there is no explicit requirement in the ICJ statute for such consent.  Additionally, the in an era of increased international cooperation and codified institutions/procedures, deference ought to be given to treaty texts over tradition.  Indeed, the ICJ Statute reflects this preference by listing international conventions before international custom in the court’s list of applicable authorities.[21]

Thus, following the interpretive principles of the VCLT, and observing the express purpose of the UN, of which the ICJ is a branch, international law dictates that the ICJ should exercise its discretion and issue a judgment on the merits of the questions referred to it by the General Assembly in Resolution 71-292.

[1] Ryan Lenora Brown, Indian Ocean Islands’ Decolonization Dispute Gets Day in International Court, Christian Sci. Monitor, Sept. 11, 2018.

[2] Id.

[3] G.A. Res. 71/292, at 2 (June 22, 2017).

[4] See Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Written Comments of the United Kingdom, 1.4 (May 14, 2018), https://www.icj-cij.org/files/case-related/169/169-20180514-WRI-01-00-EN.pdf; see also, Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Written Statement of the Republic of Mauritius, 5.1-17 (Mar. 1, 2018), https://www.icj-cij.org/files/case-related/169/169-20180301-WRI-05-00-EN.pdf.

[5] Reports of International Arbitral Awards, Vol. XXXI, Part II, ¶¶1,61(Mar. 18, 2015) http://legal.un.org/riaa/cases/vol_XXXI/359-606.pdf.

[6] Id. ¶ 61.

[7] Written Statement of the Republic of Mauritius, Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, 1.9-11 (Mar. 1, 2018) https://www.icj-cij.org/files/case-related/169/169-20180301-WRI-05-00-EN.pdf.

[8] Christian Nauvel, A Return from Exile in Sight? The Chagossians and Their Struggle, 5 Nw. J. Int’l Hum. Rts. 96, 99 (2007).

[9] Brown, supra note 1.

[10] Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Written Comments of the United Kingdom, 1.4 (May 14, 2018), https://www.icj-cij.org/files/case-related/169/169-20180514-WRI-01-00-EN.pdf.

[11] Id.

[12] Id. at 1.6.

[13] Supra note 7, at 5.2–9

[14] Statute of the Int’l Court of Justice article 65, ¶1, June 26, 1945, 3 U.S.T. 1154, 33 U.N.T.S. 983.

[15] U.N. Charter art. 96, ¶1.

[16] Supra note 7, at 1.37.

[17] U.N. Treaty Collection, Chap. 23, https://treaties.un.org/Pages/ViewDetailsIII.aspx?src=TREATY&mtdsg_no=XXIII-1&chapter=23&Temp=mtdsg3&clang=_en.

[18] Vienna Convention on the Law of Treaties, art. 31, ¶1 May 23, 1969, 1155 U.N.T.S. 331.

[19] U.N. Charter art. 1, ¶2

[20] Supra note 3.

[21] Statute of the Int’l Court of Justice article 38, ¶1 (a-b), June 26, 1945, 3 U.S.T. 1154, 33 U.N.T.S. 983, https://www.icj-cij.org/en/statute#CHAPTER_IV.



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