Cañas-Jerez Treaty

The Cañas-Jerez Treaty, signed in 1858 between Nicaragua and Costa Rica, addressed boundary disputes concerning the San Juan River. This treaty established that the San Juan River belonged to Nicaragua, but granted Costa Rica rights to commercial access and "free and perpetual" navigation.1

Throughout the 19th and 20th centuries, interpretations of this treaty led to frequent disagreements, particularly when the river was considered as a potential canal route. These disputes were often resolved through arbitration. In the early 21st century, Nicaragua imposed restrictions on Costa Rica's river usage, prompting Costa Rica to bring the issue before the International Court of Justice. In 2009, the court ruled that Costa Rica retained free navigation rights for commerce and tourism but could not exercise policing functions on the river, while Nicaragua maintained control over river traffic.1