Mare clausum

Mare clausum is a Latin term meaning "closed sea." It refers to a navigable body of water, such as a sea, that is under the jurisdiction of a single nation and is closed to other nations. This concept is the subject of Mare clausum, a work by John Selden published in 1635. Selden's book was a justification for one nation's control over the high seas, written in response to Hugo Grotius's Mare liberum (1609), which argued for the freedom of the seas. Selden was a prominent English legal antiquarian and politician in the 17th century.123