212
nature of Mauritius’ rights pursuant to the 1965 Undertakings, the Tribunal held that
“the United Kingdom [was] estopped from denying the binding effect of these commitments, which the Tribunal [would] treat as binding on the United Kingdom in
view of their repeated reaffirmation after 1968”,
90
without any longer mentioning
the characterisation of the Lancaster House Undertakings as an international
agreement.
91
4.2 Ambiguities in the Interpretation of Articles 2(3) and 56(2)
UNCLOS
As pointed out above, Article 2(3) UNCLOS refers to “other rules of international
law” in providing that the exercise of sovereignty over the territorial sea is subject
to them in addition to the UNCLOS. The Tribunal firstly addressed the question
whether the reference to other rules of international law in Article 2(3) was a source
of obligations for the coastal State; in contrast to Mauritius, the United Kingdom
contended that the provision was only descriptive in nature.
92
Having considered the
authentic texts of that provision, the context thereof, the object and purpose of the
UNCLOS, and the negotiating history dating back to the 1958 Geneva Convention
on the Territorial Sea and Contiguous Zone as well as the 1956 Draft Articles on the
Law of the Sea prepared by the International Law Commission, the Tribunal eventually found that, pursuant to Article 2(3) UNCLOS, States were obliged to exercise
their sovereignty in the territorial sea in compliance with other rules of international
law.
93
The Tribunal thus proceeded to determine the scope of the reference to “other
rules of international law” in Article 2(3).
It is in this connection that the approach of the Tribunal turns out to be ambivalent. The Tribunal restricted the ambit of the expression “other rules of international
law” in consideration of the preparatory work of Article 2(3), namely the commentary of the International Law Commission to the corresponding provision in the
1956 Draft Articles on the Law of the Sea: the Tribunal concluded that the expression “other rules of international law” indicated only general rules of international
law. As a consequence, the Lancaster House Undertakings would have not come
into consideration under Article 2(3) UNCLOS, since they fell outside general international law.
90 Chagos Marine Protected Area Arbitration, para. 448 (emphasis added).
91 The Tribunal’s focus on the United Kingdom’s repetition of its commitments, rather than the
‘transformation’ of the Lancaster House Undertakings into an international agreement, emerges
also from the analysis carried out by Appleby (2015), pp. 532–533.
92 Chagos Marine Protected Area Arbitration, para. 499.
93 Ibidem, paras 500–514.
M. Gervasi
nature of Mauritius’ rights pursuant to the 1965 Undertakings, the Tribunal held that
“the United Kingdom [was] estopped from denying the binding effect of these commitments, which the Tribunal [would] treat as binding on the United Kingdom in
view of their repeated reaffirmation after 1968”,
90
without any longer mentioning
the characterisation of the Lancaster House Undertakings as an international
agreement.
91
4.2 Ambiguities in the Interpretation of Articles 2(3) and 56(2)
UNCLOS
As pointed out above, Article 2(3) UNCLOS refers to “other rules of international
law” in providing that the exercise of sovereignty over the territorial sea is subject
to them in addition to the UNCLOS. The Tribunal firstly addressed the question
whether the reference to other rules of international law in Article 2(3) was a source
of obligations for the coastal State; in contrast to Mauritius, the United Kingdom
contended that the provision was only descriptive in nature.
92
Having considered the
authentic texts of that provision, the context thereof, the object and purpose of the
UNCLOS, and the negotiating history dating back to the 1958 Geneva Convention
on the Territorial Sea and Contiguous Zone as well as the 1956 Draft Articles on the
Law of the Sea prepared by the International Law Commission, the Tribunal eventually found that, pursuant to Article 2(3) UNCLOS, States were obliged to exercise
their sovereignty in the territorial sea in compliance with other rules of international
law.
93
The Tribunal thus proceeded to determine the scope of the reference to “other
rules of international law” in Article 2(3).
It is in this connection that the approach of the Tribunal turns out to be ambivalent. The Tribunal restricted the ambit of the expression “other rules of international
law” in consideration of the preparatory work of Article 2(3), namely the commentary of the International Law Commission to the corresponding provision in the
1956 Draft Articles on the Law of the Sea: the Tribunal concluded that the expression “other rules of international law” indicated only general rules of international
law. As a consequence, the Lancaster House Undertakings would have not come
into consideration under Article 2(3) UNCLOS, since they fell outside general international law.
90 Chagos Marine Protected Area Arbitration, para. 448 (emphasis added).
91 The Tribunal’s focus on the United Kingdom’s repetition of its commitments, rather than the
‘transformation’ of the Lancaster House Undertakings into an international agreement, emerges
also from the analysis carried out by Appleby (2015), pp. 532–533.
92 Chagos Marine Protected Area Arbitration, para. 499.
93 Ibidem, paras 500–514.
M. Gervasi