Helga Law Journal - 01.01.2021, Qupperneq 65

Helga Law Journal Vol. 1, 2021
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Dr. Snjólaug Árnadóttir
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been given due publicity with submission of data to the UNSG, and those that
have not.79 They suggest that UNCLOS might be interpreted in such a way as to
allow all States to freeze their maritime limits by depositing information on the
limits with the UNSG and not updating such notifications to reflect receding
coastlines.80 This would entail a departure from the current interpretation of
UNCLOS, which might be possible under article 31(3) of the Vienna Convention
on the Law of Treaties, but only if supported by consistent State practice.81 Several
States have informed the ILC of relevant practice in this regard and that
demonstrates a broad understanding of the ambulatory nature of maritime limits82
but also, efforts by particularly affected States (the Pacific small island developing
States) to change the interpretation.83
The ILC’s preliminary findings on the topic of ambulatory maritime limits is
that it would be feasible to stabilise maritime entitlements.84 It might threaten legal
stability and undermine UNCLOS if States were encouraged to reinterpret the
convention and a consensus on the issue seems like a distant possibility. Another
option would be to encourage tacit acceptance of outdated maritime limits. This
might achieve the same objective, without interfering directly with the
interpretation of UNCLOS. Also, it might provide a useful degree of flexibility.
After all, Pacific island States seem more interested in fixing all maritime limits
than the United Kingdom and the United States, for example, and principles of
equity would support the notion that vulnerable States enjoy flexibility. However,
it would be difficult to reconcile regional differences in the interpretation or
application of UNCLOS.
Maritime limits can be tacitly accepted in a legally binding manner. This can
make them enforceable against other States, even if they do not conform to the
maritime entitlements afforded to States under UNCLOS, or consonant
customary international law. This process is called acquiescence and it
demonstrates ‘tacit recognition manifested by unilateral conduct which the other
party may interpret as consent’.85 Although consent-based, the relationship
established through acquiescence ‘between the author State and the addressee or
addressees […] is distinct from a treaty relationship’.86

79 UN Doc A/CN.4/740 (n 29) para 143.
80 Ibid, para 104(e) and (f).
81 Note that the ‘possibility of amending or modifying a treaty by subsequent practice of the parties
has not been generally recognized’: GAOR, ‘Report of the International Law Commission, Sixty-eighth
session’ (2 May-10 June and 4 July-12 August 2016) UN Doc A/71/10, 118, 122.
82 See UN Doc A/CN.4/740 (n 29) paras 87-88.
83 Ibid paras 84-86.
84 Ibid para 190.
85 Delimitation of the Maritime Boundary in the Gulf of Maine Area (Canada/United States of
America) (Judgment) [1984] ICJ Rep 246, para 130.
86 ILC, ‘Ninth report on unilateral acts of States’ (6 April 2006) UN Doc A/CN.4/569 and Add.1, para
128.
contemporaneous evidence, and recommend final and binding continental shelf
limits excluding entitlements previously generated by the submerged territory.
It should also be noted that certain States do not have sufficient resources to
collect the necessary data and make submissions to the CLCS in order to establish
permanent continental shelf limits.76 Furthermore, it seems that non-Parties may
be precluded from submitting their data to the CLCS and establishing final and
binding limits on that basis. This is not explicitly dealt with in UNCLOS but in
Judge Heiðar’s opinion non-Parties have no such right under UNCLOS or
customary international law.77 One of the arguments supporting this conclusion is
that UNCLOS article 82, concerning revenue sharing and contributions to the
International Seabed Authority, only applies to States Parties. If States Parties
alone carry these obligations (relating to the outer continental shelf beyond 200
nm), it seems prudent that they would be the only ones benefitting from final and
binding continental shelf limits beyond 200 nm.
The International Court of Justice (ICJ) has explained that States Parties to
UNCLOS are obligated to submit relevant data to the CLCS ‘whereas the making
of a recommendation, following examination of that information, is a prerogative
of the CLCS’.78 Non-member States certainly have no obligation to make
submissions to the CLCS but this does not preclude the possibility of them
submitting their data to the CLCS. However, they would always be dependent on
the CLCS’s decision to make a recommendation and probably be placed at the end
of a long line. Consequently, not all States will be able to acquire final and binding
outer continental shelf limits but to increase their chances, States are advised to
ratify UNCLOS and submit relevant data to the CLCS in a timely fashion.
3 Tacitly Accepted Unilateral Maritime Limits
As has been noted above, unilateral limits are generally not opposable to other
States unless and insofar as they delineate entitlements afforded to coastal States
under the applicable international law. This is why unilateral limits must be
adjusted to changing coastlines to continuously meet relevant requirements. Yet,
unilaterally established maritime limits do not automatically cease to exist if they
are inconsistent with international law. On the contrary, States can continuously
rely on excessive maritime limits if they go unchallenged.
The co-chairs of the ILC’s Study Group on sea level rise have suggested that
States might be able to continuously rely on duly published maritime limits,
notwithstanding subsequent changes to relevant coasts. They suggest, in their
preliminary findings, that this might be achieved through revised interpretation of
UNCLOS. The co-chairs clearly differentiate between maritime limits that have

76 Ibid 139.
77 Tómas H Heiðar (n 73) 31.
78 Questions of the Delimitation of the Continental Shelf Between Nicaragua and Colombia Beyond 200 Nautical
Miles from the Nicaraguan Coast (n 68) para 107.