Helga Law Journal - 01.01.2021, Side 69

Helga Law Journal Vol. 1, 2021
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Dr. Snjólaug Árnadóttir
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arrangements subject to pacta sunt servanda109 or res judicata.110 The binding nature is
rooted in consent. Bilateral boundaries cannot be challenged in the same manner
as unilateral limits when circumstances change; they are generally stable and
immune to coastal changes, unless otherwise agreed. Still, unilateral limits can
fluctuate within these permanent boundaries unless specifically agreed upon,
tacitly accepted, or permanently described in accordance with UNCLOS article 76.
Overlapping territorial sea entitlements are delimited through the equidistance
method, establishing boundaries that are equally distant from baselines along
adjacent or opposite coasts, unless a different arrangement is justified by
agreement, historic title or special circumstances.111 Boundaries to the exclusive
economic zone and continental shelf are delimited on the basis of international
law to achieve equitable solutions.112 Different methods are available for
delimitation of such boundaries but coastal geography is always of pivotal
importance. International courts and tribunals have confirmed this on several
occasions.113 The size of coastal features and their distance from the mainland can
be decisive in the delimitation process114 but these factors can undergo significant
changes as sea levels rise and coastlines recede.
States may agree to revise maritime boundaries, whether established by
agreements or judicial decisions. The consent to revise settled boundaries can flow
from the terms of the original agreement or a subsequent agreement. Mutual
revision of maritime boundaries naturally requires the consent of all relevant
parties and a State suffering from loss of territory will not be easily persuaded to
construct a new maritime boundary when there is no legal obligation to do so.
However, fundamental changes to coastal geography may justify revision or
termination of bilateral maritime boundaries, despite the objection of one or more
parties to the dispute.
The principle of pacta sunt servanda does not provide that all agreements remain
inviolable until the end of time.115 On the contrary, States can be released from
treaty obligations through peaceful means under the doctrine of rebus sic stantibus,
when circumstances leading to the conclusion of a treaty have changed and

109 Frontier Dispute (Burkina Faso v Republic of Mali) (Judgment) [1986] ICJ Rep 554, 577, para 46.
110 Territorial and Maritime Dispute (Nicaragua v Colombia) (Application by Honduras for Permission to
Intervene) [2011] ICJ Rep 348, 368, para 67.
111 UNCLOS article 15.
112 UNCLOS articles 74 and 83.
113 See e.g. United Kingdom/France (n 6), para 84; North Sea Continental Shelf (n 6), para 96; Cameroon v
Nigeria: Equatorial Guinea intervening (n 6), para 295; Delimitation of the Exclusive Economic Zone and the
Continental Shelf (Barbados v Trinidad and Tobago) (Arbitral Award) [2006] RIAA volume XXVII, 147, para
288 and Continental Shelf (Tunisia/Libyan Arab Jamahiriya) (Judgment) [1982] ICJ Rep 18, para 126.
114 See e.g. Nicaragua v Colombia (n 56) para 202.
115 Rein Müllerson, ‘The ABM Treaty: Changed Circumstances, Extraordinary Events, Supreme
Interests and International Law’ (2001) 50 International and Comparative Law Quarterly 509, 525.
UNSG, or earlier, to avoid acquiescence. In the Black Sea case, the Court deemed
a basepoint on the seaward end of Sulina dyke to be irrelevant for the delimitation
of a bilateral boundary.103 Yet, the decision had no effect on the validity of
Romania’s baselines, which gave that same base point full effect. This was partly
due to the fact that Romania had submitted its data, designating a base point on
Sulina dyke, to the UNSG, in accordance with UNCLOS article 16(2), and Ukraine
had raised no objections.104
States may be able to prevent acquiescence to excessive maritime limits by
challenging them soon after they are given due publicity in accordance with
UNCLOS articles 16(2) and 76(9). However, the grounds for a challenge may arise
years later, when coastal geography undergoes significant changes, for example
with the submergence of an island. States have no reason to object to lawful
maritime limits, but they must be allowed to challenge duly established limits when
they become inconsistent with UNCLOS. After all, ‘[r]ights which have been
acquired in clear conformity with existing law have no need of the doctrine
of acquiescence to confirm their validity’.105 It should be noted that it may be
difficult to define the point in time when maritime limits become inconsistent with
international law. The status of coastal features is surveyed and depicted on
navigational charts and the disappearance of a coastal features from such charts
could give rise to challenges. However, the loss of capacity to sustain human
habitation and economic life will not be as readily apparent.
4 Agreed or Judicially Settled Maritime Boundaries
In cases where claims of two States to maritime zones overlap, the States are
obligated to establish bilateral boundaries.106 This obligation cannot be satisfied
through unilateral action. The States concerned must negotiate the establishment
of bilateral boundaries in good faith ‘with the genuine intention of achieving a
positive result’.107 If States cannot reach an agreement for the establishment of
bilateral boundaries, they can resort to the dispute settlement mechanisms
provided for in UNCLOS Part XV, including judicial settlement.108 Consequently,
the requirement to establish an agreed boundary can be satisfied by submitting a
boundary dispute to a court or a tribunal.
While unilateral limits are only opposable to other States as long as they satisfy
the requirements of UNCLOS or acquiescence, bilateral boundaries create binding

103 Maritime Delimitation in the Black Sea (Romania v Ukraine) (Judgment) [2009] ICJ Rep 61, para
217.
104 Ibid 107.
105 Ian C MacGibbon, ‘The scope of acquiescence in international law’ (1954) 31 British Yearbook of
International Law, 143, 143.
106 UNCLOS articles 15, 74 and 83.
107 Delimitation of the Maritime Boundary in the Gulf of Maine Area (n 85) para 112(1).
108 United Nations, Handbook on the Delimitation of Maritime Boundaries (UN 2001) 1.