preparing for the materialization of the parallel running through Boundary Marker No. 1, which the
delegates understood to be the maritime frontier, and that the delegates communicated such
understanding to their respective Governments.
165. The Governments of both Parties then confirmed this understanding. The Note of
5 August 1968 from the Secretary-General of Foreign Affairs of Peru to the chargé d’affaires of
“I am pleased to inform Your Honour that the Government of Peru approves in
their entirety the terms of the document signed on the Peruvian-Chilean border on
26 April 1968 by the representatives of both countries in relation to the installation of
leading marks to materialise the parallel of the maritime frontier.
As soon as Your Honour informs me that the Government of Chile is in
agreement, we will be pleased to enter into the necessary discussions in order to
determine the date on which the Joint Commission may meet in order to verify the
position of Boundary Marker No. 1 and indicate the definitive location of the towers
or leading marks . . .”
The Court notes Peru’s approval of the entirety of the document dated 26 April 1968. - 59 -
166. The Chilean response of 29 August 1968 from the Embassy of Chile to the Ministry of
Foreign Affairs of Peru is in the following terms:
“The Embassy of Chile presents its compliments to the Honourable Ministry of
Foreign Affairs and has the honour to refer to the Meeting of the Joint
Chilean-Peruvian Commission held on 25 and 26 April 1968 in relation to the study of
the installation of the leading marks visible from the sea to materialise the parallel of
the maritime frontier originating at Boundary Marker No. 1.
On this point, the Embassy of Chile is pleased to accept on behalf of the
Government of Chile the proposals which the technical representatives of both
countries included in the Act which they signed on 28 [sic] April 1968 with a view to
taking the measures for the abovementioned signalling in order to act as a warning to
fishing vessels that normally navigate in the maritime frontier zone.
Given that the parallel which it is intended to materialise is the one which
corresponds to the geographical situation indicated by Boundary Marker No. 1 as
referred to in the Act signed in Lima on 1 August 1930, the Chilean Government
agrees that an ad hoc Joint Commission should be constituted as soon as possible for
the purpose of verifying the position of this pyramid and that, in addition, the said
Commission should determine the position of the sites where the leading marks are to
167. The Act of the Chile-Peru Mixed Commission in Charge of Verifying the Location of
Boundary Marker No. 1 and Signalling the Maritime Boundary of 22 August 1969 (hereinafter the
“1969 Act”), signed by the delegates of both Parties, introduces its task using the following
“The undersigned Representatives of Chile and of Peru, appointed by their
respective Governments for the purposes of verifying the original geographical
position of the concrete-made Boundary Marker number one (No. 1) of the common
frontier and for determining the points of location of the Alignment Marks that both
countries have agreed to install in order to signal the maritime boundary and
physically to give effect to the parallel that passes through the aforementioned
Boundary Marker number one . . .” (Emphasis added.)
168. The 1969 Act recommends the rebuilding of the damaged Boundary Marker No. 1 on
its original location, which remained visible. The 1969 Act also includes a section entitled Joint
Report signed by the Heads of each Party’s Delegation, describing their task as follows:
“The undersigned Heads of Delegations of Chile and of Peru submit to their
respective Governments the present Report on the state of repair of the boundary
markers in the section of the Chile-Peru frontier which they have had the opportunity
to inspect on the occasion of the works which they have been instructed to conduct in
order to verify the location of Boundary Marker number one and to signal the
maritime boundary.” - 60 -
169. The Court observes that both Parties thus clearly refer to their understanding that the
task which they are jointly undertaking involves the materialization of the parallel of the existing
maritime frontier, with such parallel understood to run through Boundary Marker No. 1.
170. In order to determine the starting-point of the maritime boundary, the Court has
considered certain cartographic evidence presented by the Parties. The Court observes that Peru
presents a number of official maps of Arica, dated 1965 and 1966, and of Chile, dated 1955, 1961
and 1963, published by the Instituto Geográfico Militar de Chile, as well as an excerpt from
Chilean Nautical Chart 101 of 1989. However, these materials largely focus on the location of the
point “Concordia” on the coast and do not purport to depict any maritime boundary.
171. The Court similarly notes that a number of instances of Peruvian practice subsequent to
1968 relied upon by Chile are not relevant as they address the issue of the location of the
Peru-Chile land boundary.
172. The only Chilean map referred to by Peru which appears to depict the maritime
boundary along a parallel passing through Boundary Marker No. 1 is an excerpt from Chilean
Nautical Chart 1111 of 1998. This map, however, confirms the agreement between the Parties of
1968-1969. The Court considers that it is unable to draw any inference from the 30-year delay in
such cartographic depiction by Chile.
173. The evidence presented in relation to fishing and other maritime practice in the region
does not contain sufficient detail to be useful in the present circumstances where the starting-points
of the maritime boundary claimed by each of the Parties are separated by a mere 8 seconds of
latitude, nor is this evidence legally significant.
174. The Court considers that the maritime boundary which the Parties intended to signal
with the lighthouse arrangements was constituted by the parallel passing through Boundary Marker
No. 1. Both Parties subsequently implemented the recommendations of the 1969 Act by building
the lighthouses as agreed, thus signalling the parallel passing through Boundary Marker No. 1. The
1968-1969 lighthouse arrangements therefore serve as compelling evidence that the agreed
maritime boundary follows the parallel that passes through Boundary Marker No. 1.
175. The Court is not called upon to take a position as to the location of Point Concordia,
where the land frontier between the Parties starts. It notes that it could be possible for the
aforementioned point not to coincide with the starting-point of the maritime boundary, as it was
just defined. The Court observes, however, that such a situation would be the consequence of the
agreements reached between the Parties. - 61 -
176. The Court thus concludes that the starting-point of the maritime boundary between the
Parties is the intersection of the parallel of latitude passing through Boundary Marker No. 1 with
the low-water line.
VI. THE COURSE OF THE MARITIME BOUNDARY FROM POINT A
177. Having concluded that an agreed single maritime boundary exists between the Parties,
and that that boundary starts at the intersection of the parallel of latitude passing through Boundary
Marker No. 1 with the low-water line, and continues for 80 nautical miles along that parallel, the
Court will now determine the course of the maritime boundary from that point on.
178. While Chile has signed and ratified UNCLOS, Peru is not a party to this instrument.
Both Parties claim 200-nautical-mile maritime entitlements. Neither Party claims an extended
continental shelf in the area with which this case is concerned. Chile’s claim consists of a
12-nautical-mile territorial sea and an exclusive economic zone and continental shelf extending to
200 nautical miles from the coast. Peru claims a 200-nautical-mile “maritime domain”. Peru’s
Agent formally declared on behalf of his Government that “[t]he term ‘maritime domain’ used in
[Peru’s] Constitution is applied in a manner consistent with the maritime zones set out in the
1982 Convention”. The Court takes note of this declaration which expresses a formal undertaking
179. The Court proceeds on the basis of the provisions of Articles 74, paragraph 1, and 83,
paragraph 1, of UNCLOS which, as the Court has recognized, reflect customary international law
(Maritime Delimitation and Territorial Questions between Qatar and Bahrain (Qatar v. Bahrain),
Merits, Judgment, I.C.J. Reports 2001, p. 91, para. 167; Territorial and Maritime Dispute
(Nicaragua v. Colombia), Judgment, I.C.J. Reports 2012 (II), p. 674, para. 139). The texts of these
provisions are identical, the only difference being that Article 74 refers to the exclusive economic
zone and Article 83 to the continental shelf. They read as follows:
“The delimitation of the exclusive economic zone [continental shelf] between
States with opposite or adjacent coasts shall be effected by agreement on the basis of
international law, as referred to in Article 38 of the Statute of the International Court
of Justice, in order to achieve an equitable solution.”
180. The methodology which the Court usually employs in seeking an equitable solution
involves three stages. In the first, it constructs a provisional equidistance line unless there are
compelling reasons preventing that. At the second stage, it considers whether there are relevant
circumstances which may call for an adjustment of that line to achieve an equitable result. At the
third stage, the Court conducts a disproportionality test in which it assesses whether the effect of
the line, as adjusted, is such that the Parties’ respective shares of the relevant area are markedly
disproportionate to the lengths of their relevant coasts (Maritime Delimitation in the Black Sea
(Romania v. Ukraine), Judgment, I.C.J. Reports 2009, pp. 101-103, paras. 115-122; Territorial
and Maritime Dispute (Nicaragua v. Colombia), Judgment, I.C.J. Reports 2012 (II), pp. 695-696,
paras. 190-193). - 62 -
181. In the present case, Peru proposed that the three-step approach be followed in the
delimitation of the maritime boundary between the two States. Peru makes the three following
points. First, the relevant coasts and the relevant area within which the delimitation is to be
effected are circumscribed by the coasts of each Party lying within 200 nautical miles of the
starting-point of their land boundary. The construction of a provisional equidistance line within
that area is a straightforward exercise. Secondly, there are no special circumstances calling for an
adjustment of the provisional equidistance line and it therefore represents an equitable maritime
delimitation: the resulting line effects an equal division of the Parties’ overlapping maritime
entitlements and does not result in any undue encroachment on the projections of their respective
coasts or any cut-off effect. Thirdly, the application of the element of proportionality as an ex post
facto test confirms the equitable nature of the equidistance line.
182. Chile advanced no arguments on this matter. Its position throughout the proceedings
was that the Parties had already delimited the whole maritime area in dispute, by agreement, in
1952, and that, accordingly, no maritime delimitation should be performed by the Court.
183. In the present case, the delimitation of the maritime area must begin at the endpoint of
the agreed maritime boundary which the Court has determined is 80 nautical miles long (Point A).
In practice, a number of delimitations begin not at the low-water line but at a point further seaward,
as a result of a pre-existing agreement between the parties (Delimitation of the Maritime Boundary
in the Gulf of Maine Area (Canada/United States of America), Judgment, I.C.J. Reports 1984,
pp. 332-333, para. 212; Land and Maritime Boundary between Cameroon and Nigeria
(Cameroon v. Nigeria: Equatorial Guinea intervening), Judgment, I.C.J. Reports 2002,
pp. 431-432, paras. 268-269; Maritime Delimitation in the Black Sea (Romania v. Ukraine),
Judgment, I.C.J. Reports 2009, p. 130, para. 218). The situation the Court faces is, however,
unusual in that the starting-point for the delimitation in this case is much further from the coast:
80 nautical miles from the closest point on the Chilean coast and about 45 nautical miles from the
closest point on the Peruvian coast.
184. The usual methodology applied by the Court has the aim of achieving an equitable
solution. In terms of that methodology, the Court now proceeds to the construction of a provisional
equidistance line which starts at the endpoint of the existing maritime boundary (Point A).
185. In order to construct such a line, the Court first selects appropriate base points. In view
of the location of Point A at a distance of 80 nautical miles from the coast along the parallel, the
nearest initial base point on the Chilean coast will be situated near the starting-point of the
maritime boundary between Chile and Peru, and on the Peruvian coast at a point where the arc of a
circle with an 80-nautical-mile radius from Point A intersects with the Peruvian coast. For the
purpose of constructing a provisional equidistance line, only those points on the Peruvian coast
which are more than 80 nautical miles from Point A can be matched with points at an equivalent
distance on the Chilean coast. The arc of a circle indicated on sketch-map No. 3 is used to identify
the first Peruvian base point. Further base points for the construction of the provisional
- 63 -
equidistance line have been selected as the most seaward coastal points “situated nearest to the area
to be delimited” (Maritime Delimitation in the Black Sea (Romania v. Ukraine), Judgment, I.C.J.
Reports 2009, p. 101, para. 117). These base points are situated to the north-west of the initial base
point on the Peruvian coast and south of the initial base point on the Chilean coast. No points on
the Peruvian coast which lie to the south-east of that initial point on that coast can be matched with
points on the Chilean coast, as they are all situated less than 80 nautical miles from Point A (see
sketch-map No. 3: Construction of the provisional equidistance line).
186. The provisional equidistance line thus constructed runs in a general south-west
direction, almost in a straight line, reflecting the smooth character of the two coasts, until it reaches
the 200-nautical-mile limit measured from the Chilean baselines (Point B). Seaward of this point
the 200-nautical-mile projections of the Parties’ coasts no longer overlap.
187. Before continuing the application of the usual methodology, the Court recalls that, in its
second submission, Peru requested the Court to adjudge and declare that, beyond the point where
the common maritime boundary ends, Peru is entitled to exercise sovereign rights over a maritime
area lying out to a distance of 200 nautical miles from its baselines (see paragraphs 14 to
15 above). This claim is in relation to the area in a darker shade of blue in sketch-map No. 2 (see
paragraph 22 above).
188. Peru contends that, in the maritime area beyond 200 nautical miles from the Chilean
coast but within 200 nautical miles of its own coast, it has the rights which are accorded to a coastal
State by general international law and that Chile has no such rights.
Chile in response contends that the 1952 Santiago Declaration establishes a single lateral
limit for all maritime areas of its States parties whether actual or prospective, invoking the
reference in paragraph II of the Declaration to “a minimum distance of 200 nautical miles”.
189. Since the Court has already concluded that the agreed boundary line along the parallel
of latitude ends at 80 nautical miles from the coast, the foundation for the Chilean argument does
not exist. Moreover, since the Court has decided that it will proceed with the delimitation of the
overlapping maritime entitlements of the Parties by drawing an equidistance line, Peru’s second
submission has become moot and the Court need not rule on it.
190. After Point B (see paragraph 186 above), the 200-nautical-mile limits of the Parties’
maritime entitlements delimited on the basis of equidistance no longer overlap. The Court
observes that, from Point B, the 200-nautical-mile limit of Chile’s maritime entitlement runs in a
generally southward direction. The final segment of the maritime boundary therefore proceeds
from Point B to Point C, where the 200-nautical-mile limits of the Parties’ maritime entitlements
intersect. Arc of a circle with a radius of
80 nautical miles from Point A
Agreed maritime boundary
200 nautical miles
from Chile's coast
from Peru's coast
200 nautical miles
Construction of the
provisional equidistance line
This sketch-map has been prepared
Sketch-map No. 3:
for illustrative purposes only.
Mercator Projection (18° 20' S)
- 64 -- 65 -
191. The Court must now determine whether there are any relevant circumstances calling for
an adjustment of the provisional equidistance line, with the purpose, it must always be recalled, of
achieving an equitable result. In this case, the equidistance line avoids any excessive amputation of
either State’s maritime projections. No relevant circumstances appear in the record before the
Court. There is accordingly no basis for adjusting the provisional equidistance line.
192. The next step is to determine whether the provisional equidistance line drawn from
Point A produces a result which is significantly disproportionate in terms of the lengths of the
relevant coasts and the division of the relevant area. The purpose is to assess the equitable nature
of the result.
193. As the Court has already noted (see paragraph 183 above), the existence of an agreed
line running for 80 nautical miles along the parallel of latitude presents it with an unusual situation.
The existence of that line would make difficult, if not impossible, the calculation of the length of
the relevant coasts and of the extent of the relevant area, were the usual mathematical calculation of
the proportions to be undertaken. The Court recalls that in some instances in the past, because of
the practical difficulties arising from the particular circumstances of the case, it has not undertaken
that calculation. Having made that point in the case concerning the Continental Shelf (Libyan Arab
Jamahiriya/Malta) (Judgment, I.C.J. Reports 1985, p. 53, para. 74), it continued in these terms:
“if the Court turns its attention to the extent of the areas of shelf lying on each side of
the line, it is possible for it to make a broad assessment of the equitableness of the
result, without seeking to define the equities in arithmetical terms” (ibid., p. 55,
More recently, the Court observed that, in this final phase of the delimitation process, the
calculation does not purport to be precise and is approximate; “[t]he object of delimitation is to
achieve a delimitation that is equitable, not an equal apportionment of maritime areas” (Maritime
Delimitation in the Black Sea (Romania v. Ukraine), Judgment, I.C.J. Reports 2009, p. 100,
para. 111; see similarly Maritime Delimitation in the Area between Greenland and Jan Mayen
(Denmark v. Norway), Judgment, I.C.J. Reports 1993, pp. 66-67, para. 64, and p. 68, para. 67,
referring to difficulties, as in the Continental Shelf (Libyan Arab Jamahiriya/Malta) case, in
defining with sufficient precision which coasts and which areas were to be treated as relevant; and
Land and Maritime Boundary between Cameroon and Nigeria (Cameroon v. Nigeria: Equatorial
Guinea intervening), Judgment, I.C.J. Reports 2002, pp. 433-448, paras. 272-307, where although
the Court referred to the relevant coastlines and the relevant area, it made no precise calculation of
them). In such cases, the Court engages in a broad assessment of disproportionality.
194. Given the unusual circumstances of this case, the Court follows the same approach here
and concludes that no significant disproportion is evident, such as would call into question the
equitable nature of the provisional equidistance line.
195. The Court accordingly concludes that the maritime boundary between the two Parties
from Point A runs along the equidistance line to Point B, and then along the 200-nautical-mile limit
measured from the Chilean baselines to Point C (see sketch-map No. 4: Course of the maritime
Sketch-map No. 4:
Course of the maritime boundary
This sketch-map has been prepared
for illustrative purposes only.
Mercator Projection (18° 20' S)