Subsidies present thorny problems for the international trading system. The legitimate activities of governments inevitably affect the economic position of firms within their jurisdictions, yet the perception sometimes arises that government programs confer an unacceptable advantage on those firms. The controversial task of determining which sorts of government activities create unacceptable advantages, and what to do about them, has occupied an important place on the agenda of the WTO/GATT system since its inception. This paper provides an introduction to the emergence of measures on Countervailing Duties and issues that bear the regulation of subsidies and countervailing measures.