Political philosophers throughout history have been shocked by the dictum of Ulpian that Because it pleases the prince, it has the force of law ,2 and have asked whether there are not moral principles which a legislator may not contravene, whatever the scope of his constitutional powers. The philosophers\u27 answers have been of crucial importance in the development of western legal thought and have influenced the content both of national constitutions and of national and international bills of rights. The reasoning, however, underlying those answers has usually been of an a priori character, based on the acceptance of theories of natural law which do not today attract universal acceptance. It is true that, if one probes beneath the surfac...