The "Right Mix" and "Ambiguities" in Particular Customs: A Few Remarks on the Navigational and Related Rights Case

Customary international law can be general or particular. In the Navigational and Related Rights case, handed down in 2009, the International Court of Justice decided that a bilateral custom had arisen between Nicaragua and Costa Rica concerning the right to fish of the inhabitants of the two banks for subsistence purposes. The way the Court established such a right raises certain questions about the nature of custom, the process to assess it, the subjects considered, and the standard necessary to prove it.