199
settlement of the land sovereignty dispute over the Chagos Archipelago was necessary for the identification of the coastal State. It characterised Mauritius’ first submission as relating to the interpretation and application of the UNCLOS,
38
and, on
the merits, just addressed the “central question” concerning the lawfulness of the
excision of the Chagos Archipelago in the light of the “legal principles of decolonization” and the principle of self-determination.
39
Nonetheless, one may opine that a de facto ascertainment would have been sufficient for the interpretation and application of the term ‘coastal State’. On the basis
of a de facto approach, the Tribunal would have probably considered the United
Kingdom as the coastal State and thus as the State entitled to declare the Marine
Protected Area: it is the United Kingdom that has exercised sovereign powers over
the Chagos Archipelago since 1965. In this connection, it is worth recalling that the
United Kingdom cleared the Chagos Archipelago of all of its inhabitants and leased
the islands to the United States.
40
However, considering the United Kingdom as the coastal State would have been
but a matter of fact without prejudice for any future settlement of the sovereignty
dispute over the Chagos Archipelago.
41
Indeed, three reasons should have induced
the Tribunal at least to regard the factual approach as an option.
38 Dissenting and Concurring Opinion, para. 45.
39 Ibidem, para. 70. As mentioned above, the minority deemed “it permissible to decide incidentally
about sovereignty issues” (ibidem, respectively para. 45).
40 See supra, para. 1.
41 The adoption of a factual approach to determine the coastal State for the purposes of UNCLOS
interpretation and application should not be confused with the consideration of the effectivité as the
foundation of the sovereignty over a disputed land. In the light of the International Court of Justice
case law concerning disputed territories or boundaries, the role of the effectivité depends on the
legal title: it is only in the absence of the latter that the former is decisive. On the one hand, the
effectivité will merely corroborate the legal title if it is consonant therewith; on the other, the legal
title will prevail if the effectivité does not correspond to it. In this connection, see ICJ, Frontier
Dispute (Burkina Faso v. Mali), Judgment, 22 December 1986, para. 63; ICJ, Territorial Dispute
(Libya v. Chad) Judgment, 3 February 1994, paras 75–76; ICJ, Sovereignty over Pulau Ligitan and
Pulau Sipadan (Indonesia v. Malaysia) Judgment, 17 December 2002, para. 126; ICJ, Territorial
and Maritime Dispute (Nicaragua v. Colombia) 19 November 2012, para. 66. As a result, before
settling the land sovereignty dispute over the Chagos Archipelago by virtue of the effectivité, the
question about the characterisation of the 1965 Lancaster House Undertakings on the detachment
of the Archipelago as a legal title held by the United Kingdom should primarily be answered. Were
the 1965 Lancaster House Undertakings not to be considered as a legal title, for instance because
of their irrelevance in international law, the role of the effectivité as the foundation of the United
Kingdom’s sovereignty would arguably be undermined by Mauritius’ protests claiming sovereignty over the Chagos Archipelago at least since the 1980s. Were the 1965 Lancaster House
Undertakings to be considered as an international agreement as the Tribunal seemingly stated in
the Award, they could be deemed to be null and void or to have terminated because of their incompatibility with the self-determination principle as a peremptory norm under Articles 53 and 64 of
the 1969 Vienna Convention on the Law of Treaties. From a broader perspective, the question
would also arise about the applicability of the effectivité to settle the land sovereignty dispute over
the Chagos Archipelago should the detachment of the Archipelago be considered a breach of the
self-determination principle as a peremptory norm or an erga omnes obligation: it is well known
that the acquisition of territory in breach of ius cogens norms or erga omnes obligations represents
The Interpretation of the United Nations Convention on the Law of the Sea…
settlement of the land sovereignty dispute over the Chagos Archipelago was necessary for the identification of the coastal State. It characterised Mauritius’ first submission as relating to the interpretation and application of the UNCLOS,
38
and, on
the merits, just addressed the “central question” concerning the lawfulness of the
excision of the Chagos Archipelago in the light of the “legal principles of decolonization” and the principle of self-determination.
39
Nonetheless, one may opine that a de facto ascertainment would have been sufficient for the interpretation and application of the term ‘coastal State’. On the basis
of a de facto approach, the Tribunal would have probably considered the United
Kingdom as the coastal State and thus as the State entitled to declare the Marine
Protected Area: it is the United Kingdom that has exercised sovereign powers over
the Chagos Archipelago since 1965. In this connection, it is worth recalling that the
United Kingdom cleared the Chagos Archipelago of all of its inhabitants and leased
the islands to the United States.
40
However, considering the United Kingdom as the coastal State would have been
but a matter of fact without prejudice for any future settlement of the sovereignty
dispute over the Chagos Archipelago.
41
Indeed, three reasons should have induced
the Tribunal at least to regard the factual approach as an option.
38 Dissenting and Concurring Opinion, para. 45.
39 Ibidem, para. 70. As mentioned above, the minority deemed “it permissible to decide incidentally
about sovereignty issues” (ibidem, respectively para. 45).
40 See supra, para. 1.
41 The adoption of a factual approach to determine the coastal State for the purposes of UNCLOS
interpretation and application should not be confused with the consideration of the effectivité as the
foundation of the sovereignty over a disputed land. In the light of the International Court of Justice
case law concerning disputed territories or boundaries, the role of the effectivité depends on the
legal title: it is only in the absence of the latter that the former is decisive. On the one hand, the
effectivité will merely corroborate the legal title if it is consonant therewith; on the other, the legal
title will prevail if the effectivité does not correspond to it. In this connection, see ICJ, Frontier
Dispute (Burkina Faso v. Mali), Judgment, 22 December 1986, para. 63; ICJ, Territorial Dispute
(Libya v. Chad) Judgment, 3 February 1994, paras 75–76; ICJ, Sovereignty over Pulau Ligitan and
Pulau Sipadan (Indonesia v. Malaysia) Judgment, 17 December 2002, para. 126; ICJ, Territorial
and Maritime Dispute (Nicaragua v. Colombia) 19 November 2012, para. 66. As a result, before
settling the land sovereignty dispute over the Chagos Archipelago by virtue of the effectivité, the
question about the characterisation of the 1965 Lancaster House Undertakings on the detachment
of the Archipelago as a legal title held by the United Kingdom should primarily be answered. Were
the 1965 Lancaster House Undertakings not to be considered as a legal title, for instance because
of their irrelevance in international law, the role of the effectivité as the foundation of the United
Kingdom’s sovereignty would arguably be undermined by Mauritius’ protests claiming sovereignty over the Chagos Archipelago at least since the 1980s. Were the 1965 Lancaster House
Undertakings to be considered as an international agreement as the Tribunal seemingly stated in
the Award, they could be deemed to be null and void or to have terminated because of their incompatibility with the self-determination principle as a peremptory norm under Articles 53 and 64 of
the 1969 Vienna Convention on the Law of Treaties. From a broader perspective, the question
would also arise about the applicability of the effectivité to settle the land sovereignty dispute over
the Chagos Archipelago should the detachment of the Archipelago be considered a breach of the
self-determination principle as a peremptory norm or an erga omnes obligation: it is well known
that the acquisition of territory in breach of ius cogens norms or erga omnes obligations represents
The Interpretation of the United Nations Convention on the Law of the Sea…