General Principles of International Law

On Monday, the ICJ delivered its judgment in the Costa Rica v. Nicaragua case, concerning navigational and related rights on the river San Juan (Registry summary; judgment). The case itself is not terribly important in the grand scheme of things, but upon reading the judgment I came across several questions of broader import that our readers might find of interest. But first just to say a bit about the facts of the case for the sake of greater comprehension. The river San Juan is on the border between Costa Rica and Nicaragua. The border, however, does not run along the thalweg of the river, as is usually the case with river borders, but is set by treaty to run along the Costa Rican coast. Thus, the entire river belongs to Nicaragua as sovereign. The question raised by the case is what are the navigational and related rights on the river of Costa Rica and its riparian communities, under the terms of the 1858 Treaty of Limits between Costa Rica and Nicaragua. The principal of these rights…