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ICJ delimits maritime boundary between Peru and Chile in the Pacific Ocean

Volterra Fietta Client Alert
30 January 2014

On 27 January 2014, the International Court of Justice (the “Court” or the “ICJ”) delivered its judgment in the Maritime Dispute (Peru v. Chile) case. The judgment reaffirms the three-step methodology of maritime delimitation usually adopted by courts and tribunals. However, it marks the first time that the ICJ has recognised the existence of a maritime boundary established by a historic tacit agreement between coastal States.


Peru instituted proceedings against Chile on 16 January 2008 in respect of a dispute concerning, on the one hand, “the delimitation of the boundary between the maritime zones of the two States in the Pacific Ocean” and, on the other, the recognition in favour of Peru of a “maritime zone lying within 200 nautical miles of Peru’s coast” but which Chile considered to be “part of the high seas”. Peru relied on Article XXXI of the Pact of Bogotá as the basis for the jurisdiction of the Court.

The central issue in dispute was whether Peru and Chile had previously agreed upon a maritime boundary. Both Parties agreed that the land boundary between the two countries was established by the 1929 Treaty of Lima.
Peru submitted that there was no pre-existing maritime boundary between the Parties and accordingly requested the Court to delimit the maritime zones between Peru and Chile, using a line equidistant from the baselines of both Parties. Peru further requested the Court to declare Peru’s entitlement to exercise exclusive sovereign rights and jurisdiction within an area situated within 200 nautical miles (“nm”) of its baselines, but more than 200 nm from Chile’s baselines, referred to by Peru as the “outer triangle” and by Chile as the “alta mar” (see map below).

Chile argued that the Parties had already delimited their maritime boundary by agreement and that the boundary established under the Santiago Declaration of 1952 followed the parallel of latitude passing through the most seaward boundary marker of the land boundary between Peru and Chile (a point referred to as Hito No.1), extending to a minimum of 200 nm. Accordingly, Chile requested that Peru’s claim be dismissed in its entirety. The respective claims of the Parties are indicated on the map below, which is taken from the Court’s judgment.


The Judgment

The Court first examined the various agreements referred to by the Parties to determine whether an international maritime boundary was already in existence. In 1947, Chile and Peru both unilaterally issued proclamations (the “1947 Proclamations”) concerning the extension of their jurisdiction to a distance of 200 nm from their respective coasts. The Parties disagreed on the content and legal significance of the 1947 Proclamations, as well as their legal nature. The Court held that the 1947 Proclamations did not establish a maritime boundary, nor did they reflect a shared understanding of the Parties concerning maritime delimitation or the method to be used to delimit the eventual maritime boundary.

The Court then examined the Declaration of Santiago of 1952 (the “1952 Declaration”), signed by Ecuador, Peru and Chile. Paragraph IV of the 1952 Declaration states:

In the case of island territories, the zone of 200 nautical miles shall apply to the entire coast of the island or group of islands. If an island or group of islands belonging to one of the countries making the declaration is situated less than 200 nautical miles from the general maritime zone belonging to another of those countries, the maritime zone of the island or group of islands shall be limited by the parallel at the point at which the land frontier of the States concerned reaches the sea.

Chile argued that paragraph IV necessarily assumed a general maritime delimitation between Peru and Chile extending to 200 nm as, if no general maritime zones had been delimited, it would be impossible to know if an island was within 200 nm of the “general maritime zone” of the neighbouring State. This submission was rejected by the Court. The Court held that the 1952 Declaration was a treaty but that it did not constitute an agreement to the establishment of a maritime boundary. Interpreting the 1952 Declaration according to the ordinary meaning of its terms, the Court found that the Parties had only agreed on the limits of certain insular maritime zones and the zones generated by the continental coasts which abut such insular maritime zones.

Chile also relied on the provisions of subsequent agreements concluded with Ecuador and Peru, and Peru alone, in support of its submission that the 1952 Declaration established a general maritime boundary between Peru and Chile. In this context, the Court examined the 1954 Special Maritime Frontier Zone Agreement (the “1954 Agreement”), concluded between Chile, Ecuador and Peru regarding violations of the maritime frontier by small fishing vessels. Article 1 of the 1954 Agreement established a special zone “at a distance of 12 nautical miles from the coast, extending to a breadth of 10 nautical miles on either side of the parallel which constitutes the maritime boundary between the two countries”. The ICJ found that the 1954 Agreement constituted an acknowledgement by the Parties that a maritime boundary was in existence, but that the Agreement gave no indication of the nature or extent of that boundary. The 1954 Agreement thus cemented a tacit agreement on a boundary that had been previously in existence between the Parties. The Court found that certain 1968-1969 lighthouse arrangements, while not constituting a maritime boundary delimitation, proceeded on the basis that a maritime boundary already existed extending along the parallel of latitude from Hito No.1.

The Court proceeded to examine the character and extent of the maritime boundary that had been established by tacit agreement. On the basis that the 1947 Proclamations and the 1952 Declaration referred to both the sea-bed and the waters above the sea-bed, making no distinction between those maritime zones, the Court concluded that the tacitly agreed boundary was a single maritime boundary applicable to the water column, the sea-bed and its subsoil.

In order to establish the extent of the boundary established by tacit agreement, the Court referred to the practice of the Parties before and after the 1954 Agreement, as well as to developments in the law of the sea at that time. As the 1954 Agreement was specifically concluded to regulate fishing activity, the Court concluded that the boundary must extend at least to the distance where such activity was taking place at the time. The Court noted that the species making up the bulk of the annual catch of Peru and Chile in the 1950s were generally found within 60 nm of the coast. Furthermore, a central concern of the Parties in the 1950s had been the exclusion of foreign long-distance fleets, and the proclamations of 200 nm maritime zones in 1947, the 1952 Declaration and further measures taken in 1954 and 1955 had to be understood in that context (the concept of a 200 nm exclusive economic zone was many years away from acceptance in the 1950s).
On the basis of 1950s fishing practices and the law of the sea existing at the time, the ICJ concluded that the agreed maritime boundary did not extend beyond 80 nm from its starting-point. Evidence submitted about subsequent legislative practice, enforcement activities and international negotiations of the Parties did not alter this conclusion.

The Court found that the 1968-1969 lighthouse arrangements provided compelling evidence that the maritime boundary followed the parallel that passed through Hito No.1, and that the starting point of the boundary was thus the intersection of the parallel of latitude passing through Hito No.1 with the low-water line. The resulting boundary, which followed that parallel of latitude for 80nm from the low-water line to Point A, is illustrated on the map below.

The Court then addressed the delimitation of the boundary beyond Point A following its established three-step methodology. At the first stage, the Court constructed a provisional equidistance line, drawing a circle with an 80 nm radius from Point A, in order to determine the relevant base points on the Peruvian coast. This equidistance line was extended out to 200 nm from the Chilean coast (to Point B). The Court did not find it necessary to address the submission of Peru regarding the ‘outer triangle’, since it had delimited the Parties’ overlapping maritime entitlements in the outer sector beyond Point A by way of an equidistance line. The Peruvian entitlement (and thus the maritime boundary) extends south of Point B to Point C for approximately 22 nm following the 200 nm limit of Chile.

At the second stage, the Court found that there were no relevant circumstances calling for adjustment of the provisional equidistance line. At the third stage, in examining whether the result achieved was significantly disproportionate in relation to the lengths of the relevant coasts, the Court recalled its previous jurisprudence explaining that the object of delimitation was to achieve an equitable result, not an equal apportionment of maritime areas. As the existence of an agreed boundary running along a parallel for 80 nm would make the calculation of the relevant coastal length and coastal areas “difficult, if not impossible”, the Court did not conduct a precise calculation of ratios, but instead broadly assessed any possible disproportionality. It concluded that there was no “significant disproportion” such as would call into question the equitable nature of the provisional equidistance line beyond Point A.

The resulting territorial sea, continental shelf and exclusive economic zone boundary delimited by the Court is illustrated on the map below. Since there is no question of continental shelf entitlement beyond 200 nm in the disputed area, the boundary ends at Point C.



The Court’s judgment represents a compromise of sorts between the positions advanced by the Parties, with Chile’s claims upheld to Point A and Peru’s claims prevailing beyond that point. In this sense, as is often the case following proceedings before the ICJ, there is something in the judgment for each Party.

This is the first case where the ICJ has recognised that a maritime boundary was (at least in part) established by tacit agreement between two coastal States. This aspect of the decision can be compared broadly with the Tunisia/Libya Continental Shelf case of 1982, where the Court considered a de facto line acted on by the Parties in the granting of oil concessions as relevant to the choice of delimitation method in the landward sector of the boundary. In the absence of written evidence of the boundary tacitly agreed upon between Chile and Peru, the Court determined the extent of their agreed boundary by reference to 1950s fishing practices and the law of the sea as it existed at that time.

The Court took a relatively proactive approach to the assessment of the evidence in an attempt to identify what was the outer point of the tacitly agreed boundary. Chile had referred to certain FAO fisheries statistics in four brief paragraphs in its Memorial and in two sentences in oral proceedings to demonstrate how it had benefitted from the 1952 Declaration. The Court relied on these statistics to determine which species were fished in the 1950s. It relied also on statements made by the Peruvian delegate to the 1958 United Nations Conference on the Law of the Sea to determine the range of such species at the time. The 80 nm outer point established by the Court thus can be regarded as having some broad evidential basis, though it lacks any specific empirical basis. Notably, six members of the Court, including President Tomka, voted against that part of the judgment holding that the tacitly agreed boundary ended at Point A.

The delimitation beyond Point A follows the orthodox three-step delimitation approach in what was an unexceptional geographic setting. As such, that part of the judgement adds little to the corpus of modern international law on maritime delimitation.