In a dispute submitted to the International Court of Justice 6 years ago, the Court yesterday released its decision on the maritime boundary between Peru and Chile. The case addressed the ambiguity of an earlier agreement that established a boundary along a line of latitude extending westward from a point on or near the coast. This prior agreement extended the boundary beyond the territorial sea, but did not specify a specific distance for its maximum event seaward. Chile contended that the line of latitude extended out to the outer extent of its EEZ and further contented that the boundary extended further to serve as the southern boundary of Peru's maritime jurisdiction not only between Peru and Chile but between Peru and the high seas as well.
The Court's decision is favorable to Peru. While it recognizes the line of latitude as applying to the western side of the common boundary, it only follows the line outward to 80 miles. It then inclines to the southwest along an equidistant point 80 miles from the coastal baseline out to the 200 nm limit of the Chilean EEZ, then turns to the south to include a small triangle outside the Chilean EEZ that is within 200nm of Peru's coastal baseline.
Source: Peru This Week website
While this appears to be a significant loss to Chile, the maintenance of the line of latitude out to 80 nm retains the area of the most productive coastal fisheries that has been included by Chile's original claim.
Chile has asked that Peru accede to the UN Convention on the Law of the Sea before the Court's decision is implemented by Chile. Accession to UNCLOS has been considered within the Peruvian government in recent years, but no action to that end has been taken.
In a situation not unfamiliar to compromises on boundaries that involve compromise of the maximum initial claim, Santiago has seen an adverse minority reaction to the acceptance of the ICJ decisions:
There was also a tense situation in the Chilean capital shortly after the decision was made public. A small group of neo-nazis and other disgruntled Chileans protested in Santiago’s Plaza de Armas, nicknamed “Little Lima” for the large Peruvian presence there. They called for a war with Peru and called the handing over of territory to Chile’s northern neighbor treason. A second group, some of whom dressed as military personnel from the Pacific War, was also seen in front of the presidential palace, La Moneda.
source: Santiago Times report on Chilean response to ICJ decision
In addition, Chile claims that the line of latitude for the maritime boundary begins at "Border marker number 1" based on a reading of historical intent, which is a point 264 meters landward of the coast. Peru has contended that the boundary should be the line of latitude passing through Punto Concordia on the coast and on an extension of the land boundary passing to and through Border Marker #1. This results in a coastline where the land side is part of Peru's sovereign territory yet the water falls under Chile's maritime jurisdiction.
Source: Peru This Week website
And here is a link to the original application made by Peru to the ICJ on January 16, 2008.