The article, written jointly by a law professor and political science professor, endeavors to explain why the United States is particularly resistant to various efforts at international harmonization of antitrust law. While others have wrangled with this question over the years, none has assessed the question from within the broader political framework in which all relations between nations exist. Our article endeavors to fill this intellectual gap.Existing efforts to describe or explain the lack of international harmonization have generally focused on the direct economic effects, and the narrow political difficulties, of the harmonization of competition laws through certain international mechanisms, most notably the WTO and the OECD. Largely absent in these accounts is a background theory of international politics against which the practicalities – and the ultimate desirability – of international competition law harmonization can be assessed. Our article presents such a theory. It places the conflict over international competition laws within the larger framework of international relations, and in so doing draws out some novel and important implications of the debate.An important insight of this Article is that, largely independent of the economic calculus regarding the costs and benefits of entering into a multilateral international antitrust agreement, there is an inherent “transaction benefit” in the act of engaging in political exchange between states. Traditional economic and legal analyses of international relations have focused largely on the choice of organizational form (market exchange (no explicit agreement) versus bilateral versus multilateral institutions) and the likelihood and nature of compliance with each type in the absence of a central enforcement authority. By contrast, we strive here to develop a political theory of international law which accounts on the one hand for the costs of entering into international agreements, but also accounts for the state’s political preference for a specific form of agreement. The novel implication of this understanding is that, by crafting international agreements in which the other parties are made to alter their domestic institutions as a condition of agreement, the dominant state (here, the United States) receives a credible commitment from the other state as to its willingness to adhere to the terms of the specific agreement under negotiation which, in the absence of centralized enforcement, might not otherwise be forthcoming. Additionally, the alteration of domestic institutions in a manner directed by the dominant state will in and of itself be viewed as a benefit of the agreement. By facilitating domestic normative change, the dominant state will gain a measure of transformative power from the change of domestic institutions. As a result, nations derive political benefits from international agreements in a way that transcends the substance of the agreements themselves.The process of internationalizing and harmonizing competition law provides fertile ground in which to examine these ideas. Negotiations over antitrust policy are particularly important because as government barriers to trade have fallen they may well be replaced by private barriers. At the same time, as tariff barriers to trade have fallen, governments may resort to the discriminate application of antitrust law to maintain preferred local monopolies, and therefore to make payoffs to politically important constituents. The prospects for the illiberal application of antitrust laws and their economic importance make the debates over their form an issue of abiding concern for the process of global economic liberalization.