Keynote Speech on the 50th Anniversary of the Vienna Convention on the Law of Treaties Department of Foreign Affairs 26 November 2019 Justice Antonio T. Carpio (Ret.) Acting Secretary Enrique Manalo, Undersecretary Eduardo Malaya, Atty. Igor Bailen, other officials and employees of the Department of Foreign Affairs, distinguished guests, friends, a pleasant afternoon to everyone. Thank you for inviting me here this afternoon to join you in celebrating the Golden Anniversary of the Vienna Convention on the Law of Treaties. As you know, the most important source of international law are treaties. Treaties regulate relations between and among states. Treaties constitute the law between and among treaty states. Treaties must be observed faithfully between and among treaty states as expressed in the maxim pacta sunt servanda. Harmonious relations between and among treaty states can be maintained only if states uniformly apply and interpret treaties that regulate their relations. Treaties cannot operate to regulate relations and conduct of states if treaty states have different interpretations of treaties to which they are parties. There can be no effective dispute settlement between and among treaty states without uniform and universally accepted rules of treaty interpretation.

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Keynote Speech on the 50th
Anniversary of the
Vienna Convention on the Law of Treaties
Department of Foreign Affairs
26 November 2019
Justice Antonio T. Carpio (Ret.)
Acting Secretary Enrique Manalo, Undersecretary Eduardo
Malaya, Atty. Igor Bailen, other officials and employees of the
Department of Foreign Affairs, distinguished guests, friends, a
pleasant afternoon to everyone. Thank you for inviting me
here this afternoon to join you in celebrating the Golden
Anniversary of the Vienna Convention on the Law of Treaties.
As you know, the most important source of international law
are treaties. Treaties regulate relations between and among
states. Treaties constitute the law between and among treaty
states. Treaties must be observed faithfully between and
among treaty states as expressed in the maxim pacta sunt
servanda.
Harmonious relations between and among treaty states can
be maintained only if states uniformly apply and interpret
treaties that regulate their relations. Treaties cannot operate
to regulate relations and conduct of states if treaty states have
different interpretations of treaties to which they are parties.
There can be no effective dispute settlement between and
among treaty states without uniform and universally accepted
rules of treaty interpretation.

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That is the function of the Vienna Convention – the treaty we
celebrate today for its 50th
year since its signing. The Vienna
Convention is the common language used in applying and
interpreting treaties so that states are on the same
wavelength when they negotiate, conclude, apply, interpret
and terminate treaties, enabling peace and stability in the
world and the advancement of civilization in an orderly
manner.
The Vienna Convention is now deeply embedded in Philippine
jurisprudence. The Vienna Convention has been cited, in both
majority and minority opinions, in no less than 22 Supreme
Court decisions that applied and interpreted treaties entered
into by the Philippines.
The most important example of the value of the Vienna
Convention to the Philippines was the application of the
Vienna Convention in the South China Sea Arbitration at The
Hague. In its July 12, 2016 Award on the merits, the arbitral
tribunal wrestled on what constitutes a rock which can sustain
human habitation of its own so as to be to be entitled not only
to a 12-NM territorial sea, but also to a 200-NM exclusive
economic zone.
A 12-NM territorial sea around a rock one or two inches above
water at high tide is already so valuable that coastal states
fight over its sovereignty. The surface area of the 12-NM
territorial sea around a tiny rock in the middle of the South
China Sea is about 155,000 hectares, more than twice the land
area of Singapore of about 70,000 hectares, and more than
twice the land area of Metro Manila of about 63,000 hectares.

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A rock that is capable of human habitation of its own is entitled
to a 200-NM exclusive economic zone. The surface area of the
200-NM exclusive economic zone around a rock capable of
human habitation of its own is 20 times the 12-NM surface
area of a rock entitled only to a 12-NM territorial sea. That
means a rock capable of human habitation of its own can have
a maximum exclusive economic zone of about 2.58 million
hectares, 41 times larger the land area of Metro Manila or
Singapore, or one-fourth the land area of Luzon. And of
course, the state that has sovereignty over that habitable rock
owns all the fish, oil, gas and other mineral resources within
such huge maritime area consisting of the exclusive economic
zone of the habitable rock.
This was the issue when the arbitral tribunal considered
whether Itu Aba, at 46 hectares the largest geologic feature in
the Spratlys, was a rock capable or not capable of human
habitation of its own. Of course, if Itu Aba were declared a
rock capable of human habitation of its own, its 200-NM
exclusive economic zone would largely overlap with the 200-
NM exclusive economic zone of Palawan, which is situated at
a distance of about 260-NM from Itu Aba.
And the most telling consequence of such overlapping
exclusive economic zones would be that the arbitral tribunal
would have no jurisdiction over the maritime dispute in the
overlapping maritime areas, since the dispute would turn into
a maritime boundary delimitation to which China admittedly
opted out of compulsory arbitration in accordance with
UNCLOS.

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The issue of whether to submit the status of Itu Aba for
adjudication by the arbitral tribunal divided the Philippine
lawyers involved in the arbitration. One group was certain
that Itu Aba would be declared non-habitable following the
ruling in Nicaragua v. Colombia where a geologic feature
almost as large as Itu Aba was declared not capable of human
habitation of its own despite the presence of potable
freshwater well. The other group did not want to take the risk
of Itu Aba being declared habitable which would result in the
case, at least with respect to the overlapping exclusive
economic zones, being dismissed for lack of jurisdiction by the
tribunal.
The President then, Simeon Aquino III, made a Solomonic
decision: do not raise the status of Itu Aba as an issue in the
prayer of the Statement of Claim, but discuss the status of Itu
Aba in the Memorial. Thankfully, the arbitral tribunal
considered the status of Itu Aba as impliedly raised as an issue
when the Philippines claimed in its prayer that the arbitral
tribunal confirm that the Philippines has a full 200-NM
exclusive economic zone facing the South China Sea.
And how did the arbitral tribunal decide whether or not Itu
Aba was capable of human habitation of its own? Let me quote
from the arbitral ruling of 12 July 2016:
The critical element of Article 121 for the Tribunal is
its paragraph (3), which provides “rocks which cannot
sustain human habitation or economic life of their own
shall have no exclusive economic zone or continental
shelf.”

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In order to interpret this provision, the Tribunal must
apply the provisions of the Vienna Convention on the
Law of Treaties. The general rule of interpretation is
set out in Article 31 of the Vienna Convention and
provides that a treaty “shall be interpreted in good faith
in accordance with the ordinary meaning to be given
to the terms of the treaty in their context and in the
light of its object and purpose.” Further, “any
subsequent practice in the application of the treaty
which establishes the agreement of the parties
regarding its interpretation” shall be taken into
account. Pursuant to Article 32 of the Vienna
Convention, as supplementary means of
interpretation, recourse may be had to the preparatory
work of the treaty to confirm its meaning, or determine
the meaning when it is otherwise ambiguous, obscure,
or leads to a manifestly absurd or unreasonable result.
Applying Article 31 of the Vienna Convention, the arbitral
tribunal ruled that Itu Aba is not capable of human habitation
of its own, and is entitled only to a 12-NM territorial sea. Itu
Aba has no exclusive economic zone that can overlap with the
exclusive economic zone of Palawan, and thus the arbitration
did not raise any maritime boundary delimitation and
consequently the arbitral tribunal had jurisdiction over the
maritime issues raised involving the waters between the
Spratlys and Palawan.
In the Summary of its ruling, the arbitral tribunal interpreted
Article 121 and concluded that the entitlements of geologic
feature depend on “(a) the objective capacity of a feature, (b)

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in its natural condition, to sustain either (c) a stable
community of people or (d) economic activity that is neither
dependent on outside resources and not purely extractive in
nature.” The arbitral tribunal explained that the exclusive
economic zone was created for the benefit of people who
reside and settle in an island as a community and who make
the island their permanent home. If an island never had such
a population in its history, it is probably because it is incapable
of human habitation of its own.
The arbitral tribunal’s interpretation, pursuant to the Vienna
Convention, of a habitable island under Article 121 of UNCLOS
has significantly reshaped the fortunes and economies of
coastal states all over the world. Surprisingly, the greatest
beneficiary of this interpretation is China. With the arbitral
tribunal’s interpretation of a habitable island entitled to a 200-
NM exclusive economic zone, coastal states that have
sovereignty over small uninhabited islands all over the world
can no longer claim exclusive economic zones for these
islands. Clearly, many uninhabited islands will no longer be
entitled to a 200-NM exclusive economic zones as previously
claimed by the coastal states that have sovereignty over them.
Consequently, the high seas in the oceans and seas of the
world have vastly increased. In the high seas, there is freedom
of fishing – all states, coastal or landlocked, have the right to
fish in the high seas all over the world. China has the largest
fishing fleet in the world and is clearly the number one
beneficiary of the arbitral ruling in this regard.

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Moreover, China, as a member of UNCLOS, can apply with the
International Seabed Authority for a permit to explore and
exploit the mineral resources in the seabed beyond the 12-NM
territorial seas of these non-habitable islands anywhere in the
world. China, along with a handful of countries, has the
technology to mine the deep seabed. Whatever China lost in
the South China Sea arbitration, in terms of fishing rights and
mineral resources, it has more than recovered in other seas
and oceans of the world.
Incidentally, the United States, not being a member of
UNCLOS, cannot apply with the International Seabed
Authority for a permit to explore and exploit the deep seabed.
Furthermore, the exclusive economic zones that the U.S. has
claimed for its non-habitable islands in the Pacific Ocean are
now part of the high seas where China’s vast fishing fleet can
legally fish.
The South China Sea arbitration, in particular the arbitral
tribunal’s ruling of what constitutes a habitable island entitled
to a 200-NM exclusive economic zone, will re-shape the
direction of the Law of the Sea for decades to come. The
Philippines is fortunate that the Vienna Convention was there
to guide the arbitral tribunal in the interpretation of Article
121 of UNCLOS. China cannot complain because China is a
state party to both UNCLOS and the Vienna Convention.
The Vienna Convention, in the light of the overwhelming
victory of the Philippines in the South China Sea arbitration,
should reassure us to continue our faith and confidence in the

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rule of law in resolving peacefully our disputes with other
states.
Thank you and a pleasant day to everyone.