Since the 18th cent. coastal states have been held to have jurisdiction over unenclosed waters for 3 nautical mi (3.45 mi/5.55 km) from the low water line, a measure originally derived from the distance of a cannon shot. In the case of a bay up to 24 mi (39 km) wide, a line drawn from one enclosing point to the other marked the outer limit of territorial jurisdiction. A broader zone of jurisdiction to combat smuggling has long been claimed by various states, as by the United States during prohibition.
Merchant ships of all flags have the right of
innocent passage in a nation's territorial waters; the rights of nonbelligerent foreign warships in this zone, and the extent of the jurisdiction of the coastal nation's courts over ships passing through and incidents in the zone, have long been matters of debate. Fishing and mineral extraction within the zone are entirely within the control of the coastal nation. In the 20th cent., coastal nations progressively widened their claims over offshore waters, especially in the face of competition from foreign fishing fleets and in anticipation of rich oil, gas, and mineral finds on the continental shelf. The UN-sponsored Law of the Sea treaty, which went into effect in 1994, codified territorial waters of 12 nautical mi (13.8 mi/22.2 km) and an exclusive economic zone of 200 nautical mi (230 mi/370 km). In 1999, U.S. agencies were empowered by presidential proclamation to enforce American law up to 24 miles (39 km) offshore, doubling the previous limit.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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