\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.