seas, freedom of the, in international law, the principle that outside its territorial waters (see waters, territorial) a state may not claim sovereignty over the seas, except with respect to its own vessels. This principle, first established by the Romans, gives to all nations in time of peace unrestricted use of the seas for naval and commercial navigation, for fishing, and for the laying of submarine cables. From the late 15th to the early 19th cent., Spain, Portugal, and Great Britain attempted to exclude commercial rivals from parts of the open sea. Protests by other nations led to a revived acceptance of freedom of the seas. One of its strongest advocates was the United States, especially in its dispute with Great Britain preceding the War of 1812. In time of peace, freedom of the seas cannot be restricted lawfully except by international agreements, such as those regulating fisheries or the right of visit and search (see search, right of). During war, however, belligerents often assert limitations of the principle in order to facilitate the more effective conduct of hostilities, and it is then that the sharpest disagreements arise, e.g., the case of the Lusitania in World War I. Subjects of contention between neutrals and belligerents include the right to seize neutral property and persons aboard an enemy ship (see prize), the mining of sea lanes, and the exclusion of neutral vessels from enemy ports by blockade. The Law of the Sea treaty (1982, in force from 1994) established a 12-nautical-mile (22-kilometer) territorial limit for coastal nations and established an international authority to regulate seabed mining, among other provisions.
See C. J. Hill, Introduction to the Carriage of Goods By Sea (1974).