territorial sea

Territorial waters \Ter`ri*to"ri*al wa"ters\ (Internat. Law)
   The waters under the territorial jurisdiction of a state;
   specif., the belt (often called the

   {marine belt} or

   {territorial sea}) of sea subject to such jurisdiction, and
      subject only to the right of innocent passage by the
      vessels of other states.

            Perhaps it may be said without impropriety that a
            state has theoretically the right to extend its
            territorial waters from time to time at its will
            with the increased range of guns. Whether it would
            in practice be judicious to do so . . . is a widely
            different matter . . . . In any case the custom of
            regulating a line three miles from land as defining
            the boundary of marginal territorial waters is so
            far fixed that a state must be supposed to accept it
            in absence of express notice.         --W. E. Hall.
      [Webster 1913 Suppl.]