Since the end of the Second World War, the United States has followed a generally consistent policy of open trade, allowing other nations to have access to the U.S. market even though U.S. companies might not be accorded similar privileges abroad. The underlying theory reflected a view that the powerful U.S. economy would do best in a freely trading world and that the most effective way to achieve this result was to lead by example. Thus, the policy of “national treatment” was conceived, under which foreign firms would be treated in the U.S. market as though they were U.S. firms and, ideally, U.S. firms would be treated in foreign markets no differently from domestic companies in those same markets. National treatment is one of the principal underpinnings of the General Agreement on Tariffs and Trade, which, in turn, has been the cornerstone of postwar U.S. trade policy.