erritorial waters, in international law, that area of the sea immediately adjacent to the shores of a state and subject to the territorial jurisdiction of that state. Territorial waters are thus to be distinguished on the one hand from the high seas, which are common to all countries, and on the other from internal or inland waters, such as lakes wholly surrounded by the national territory or certain bays or estuaries.Historically, the concept of territorial waters originated in the controversy over the status of the sea in the formative period of modern international law in the 17th century. Although the doctrine that the sea by its nature must be free to all was eventually upheld, most commentators did recognize that, as a practical matter, a coastal state needed to exercise some jurisdiction in the waters adjacent to its shores. Two different concepts developed—that the area of jurisdiction should be limited to cannon-shot range, and that the area should be a much greater belt of uniform width adjacent to the coast—and in the late 18th century these concepts coalesced in a compromise view that proposed a fixed limit of 3 nautical miles (1 marine league, or 3.45 statute miles [5.5 km]). In 1793 the United States adopted three miles for neutrality purposes, but although many other maritime states during the 19th century came to recognize the same limit, it never won such universal acceptance as to become an undisputed rule of international law.