Question put by Judgc Cançado Trindadc:
My question is addressed to ail delegations of participants in these oral advisory
proceedings.
As recalled in paragraph (a) of the UN General Assembly's Request for an advisory
opinion of the International Court of Justice, General Assembly resolution 71/292 of22 June
2017, the General Assembly refers to obligations enshrined into successive pertinent resolutions
of its own, as from 1960, namely: General Assembly resolutions 1514 (XV) of 14 December
1960, 2066 (XX) of 16 December I 965, 2232 (XXI) of 20 December 1966, and 2357 (XXII) of
19 December 1967.
In the course of the present oral advisory proceedings, references were often made to
such resolutions by several delegations of Participants.
In your understanding, what are the legal consequences ensuing from the formation of
customary international law with the significant presence of opinio juris communis for ensuring
compliance with the obligations stated in those General Assembly resolutions?"
Thank you, Mr. President.
Written replv of the United States of America:
Question (a) of the U.N. General Assembly's request for an advisory opinion referred to
"obligations reflected in" a number of General Assembly resolutions. 1 However, as framed,
Question (a) improperly seeks to prejudge the legal answer.2 lt does so by suggesting that the
General Assembly resolutions referenced therein reflected international legal obligations binding
on the United Kingdom that would have prohibited it from establishing the British Indian Ocean
Territory (BIOT). As the Court explained in Kosovo, where a matter is capable of affecting the
answer to the question posed, " [i]t would be incompatible with the proper exercise of the judicial
function for the Court to treat that matter as having been determined by the General Assembly."3
The Court must therefore reach its own determination as to whether the resolutions cited in the
request for an advisory opinion reflected international legal obligations.
Under the terms of the U.N. Charter, General Assembly resolutions-with limited
exceptions not applicable here-are not themselves legally binding.4 The fact that the General
Assembly cited particular resolutions in the question referred to the Court does not alter the
resolutions' nonbinding nature. Nor do General Assembly resolutions themselves create
customary international law. General Assembly resolutions may provide evidence of a rule of
customary international law if they reflect an opinio juris among States that existed at the
1 U.N.G.A. Res. 71/292, Request for an advisory opinion of the International Court of Justice on the legal
consequences of the separation of the Chagos Archipelago from Mauritius in 1965 (June 22, 2017).
2 See United States Written Statement, para. 4.14.
3 Accordance with International Law of the Unilateral Declaration of Jndependence in Respect of Kosovo, Adviso,y
Opinion, J.C.J. Reports 2010, p. 403, para. 52.
4 United States Written Statement, para. 4.14, n. 98.
•
relevant time,5 provided such opinio juris was accompanied by "extensive and virtually uniform"
state practice.6 Only where these two elements are satisfied can the Court identify a rule of
customary international law.7
As explained in the United States written submissions and oral presentation, there was no
opinio juris at the time Resolution 1514 was adopted, or through the end of the 1960s, to support
the conclusion that customary international law prohibited the United Kingdom from
establishing the BIOT. 8 This Jack of opinio juris, by itself, compels the conclusion that the
General Assembly resolutions cited did not reflect international legal obligations. Moreover,
here, the other prerequisite for a rule of eustomary international law was also missing: there was
not extensive and virtually uniform State practice during the relevant period.9
Thus, the resolutions cited in the questions were not themselves binding, nor did they
reflect relevant customary international law existing at the time the BIOT was established or
when Mauritius became independent, and could not give rise to legal consequences.
5 Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, J.C.J. Reports 1996, p. 226, para. 70. See
United States Written Statement, para. 4.28; United States Written Comments, para. 3 .14.
6 North Sea Continental Shelf, Judgment, J.C.J. Reports 1969, p. 3, para. 77.
7 Jurisdictional lmmunities of the State (Germany v. /ta/y: Greece intervening), l.C.J. Reports 2012, p. 99, para. 55.
8 See United States Written Statement, paras. 4.32-4.64.
9 See United States Written Statement, paras. 4.65-4.72.
Written Reply of the United States of America to the question put by Judge Cançado Trindade at the end of the hearing held on 5 September 2018