The term "war against terrorism" must be understood in a political and not a legal sense. Since the advent of the United Nations Charter in 1945 war is no longer a right of states. The use of force must be restricted to the circumstances allowed under the Charter. To invoke the term "war" does not in itself give the United States, or any other country, belligerent rights to attack terrorists wherever they may be found, argues Professor Ivan Shearer, Challis Professor of International Law at the University of Sydney. The relevant rights must be founded in both international law and national laws as measures of prevention and enforcement.