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Expert evidence helps settle centuries-old territorial dispute

By Peter Fitzgibbon - 22nd December 2015 - 14:45

The evidence given by an expert in rivers from The University of Nottingham has been pivotal in a ruling by the International Court of Justice (ICJ) on a centuries-old border dispute between Costa Rica and Nicaragua

Professor Colin R. Thorne from the University’s School of Geography was a key witness in a trial which settled a border dispute between the Central American nations of Costa Rica and Nicaragua that has festered, and periodically flared into armed conflict, since 1858.

This dispute had previously defied the best efforts of third parties, including US President Grover Cleveland and US Army Engineer General Alexander, to find a solution.

A complex history

The dispute centred on a small patch of wetlands on the Rio San Juan river. In framing their arguments, the legal teams of both countries called on internationally-renowned river experts from globally-leading universities to help them and the judges unravel the complex history of changes in the physical geography of the largest river in Central America.

Nicaragua selected a professor at the University of California, Berkeley Campus as its lead expert, while Costa Rica chose Professor Thorne.

Professor Thorne said: “Events that provoked Costa Rica to open a case against Nicaragua in the ICJ were not disputed. In October 2010, Nicaragua excavated a canal linking the Rio San Juan – which is under Nicaragua’s sovereignty, with a coastal waterbody called the Harbor Head Lagoon, which is also Nicaraguan territory. The dispute focused on whether that canal ran through Costa Rican territory or not.

International law

“To back up its dredging engineers, Nicaragua deployed not only units of its army but also members of the Sandinista Youth. Costa Rican Conservation Rangers in the area, which is designated as a Wetland of International Importance under the Ramsar Convention, were powerless to evict the Nicaraguan Army, even when supported by police officers - Costa Rica disbanded its army in 1947, re-allocating funding to education and conservation. Under the circumstances, Costa Rica’s only recourse was to rely on International Law as adjudicated by the UN-backed ICJ.”

The effect of diverting part of the flow in the Rio San Juan through the canal was to cut off about 3 km2 of Costa Rican territory and incorporate it into Nicaragua. Cutting the Old Growth forest to clear a path for the canal involved felling hundreds of ancient trees and disturbing rare wetland habitat occupied by multiple endangered species.

As an expert witness, Professor Thorne prepared a historical account of changes in the course of the Rio San Juan and examined whether, as Nicaragua claimed, their engineers had not dug a new channel for the river but cleaned a pre-existing branch of the river that had become clogged with silt and vegetation.

Clear ruling

Professor Thorne’s evidence, delivered in written reports, and tested under cross-examination by lead counsel for Nicaragua Mr Paul Reichler, established that no branch of the Rio San Juan had existed at the location of the new canal for over a century.

In their ruling the Court cited Professor Thorne’s expert evidence, drawing on five of his main conclusions in refuting arguments put forward by Nicaragua. The judges also ruled that in clearing wetland forest to make way for their canal, Nicaragua had caused substantive damage to wetlands in Costa Rican territory and ordered Nicaragua to compensate Costa Rica accordingly. The amount of compensation is yet to be agreed.

Professor Thorne added: “Decisions of the International Court of Justice are binding and there can be no appeal. Thus, the ICJ’s ruling yesterday finally resolves a dispute that has persisted for 157 years.”

Source: University of Nottingham (

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