Freedom of the Seas, in international law, the principle that no nation has sovereignty over ocean areas outside its territorial waters. The principle is based on the need for freedom of commerce by all nations. It developed as a protest against attempted control of the seas by Spain, Portugal, and Great Britain from the 15th century to the 19th century.
Freedom of the seas is usually unrestricted in peacetime but is often abandoned in modern warfare. The efforts of warring nations to prevent all ships from delivering goods to the enemy can easily restrict the right of a neutral nation to freedom of the seas. Such efforts on the part of Germany led the United States to abandon its neutrality during World War I.
