It is the focus of this thesis to critically evaluate the cooperative enforcement option proffered by the US authorities with a view to judging its attractiveness to other nations and its adequacy in solving problems posed by extraterritoriality in today's highly liberalized economy. In this regard, we shall see that the various models of cooperative enforcement arrangements adopted within the United States have failed to result in productive bilateral cooperation. This is due in large part, to the commitment of individual countries to satisfying national interests over cooperative obligations arising under the agreements. Because of these insufficiencies, the thesis reiterates the need for the US to actively partake in the ongoing effort within the WTO to forge global competition law.This thesis is made up of five Parts. Part I traces the origin of extraterritoriality in US antitrust law by examining changing the judicial attitude towards the extension of the Sherman Act abroad. The first section of Part II briefly catalogs international reaction to the reach of the Sherman Act into foreign territories. Part III opens with a discussion on the Cooperative Enforcement Agreements as a solution. Without necessarily underestimating the relevance of cooperation amongst antitrust enforcement agencies, the thesis laments the cooperative framework of the United States antitrust law, which has little chance of resulting in actual intercountry cooperative enforcement. In Part IV, the future of extraterritoriality in the 21st Century would be considered. Part V contains the thesis' conclusions, mainly, that the inability of cooperative enforcement framework in the US.