Abstract: This article analyses the structure of the federal merger regime of the United States. and the options selected by the Antitrust Modernization Commission to improve the allocation of enforcement responsibilities between the federal antitrust authorities and the State Attorneys General. Emphasising the complexity of policy enforcement in multi-jurisdictional settings, it offers the theory of regulatory competition as revised by regulatory co-opetition, alongside the theory of policy networks as a theoretical benchmark of effectiveness of policy enforcement in such systems. In the light of the political theory and empirical data, it finds that the US federal merger regime seems to suffer from bad network structuring stemming from information block rather than the allocation of enforcement responsibilities. The article concludes that improved information sharing mechanisms between the federal antitrust authorities and the State Attorneys General could bring about a major improvement to the system without more dramatic amendments being necessary. Consequently, it suggests that the US authorities might find it plausible to examine the mechanisms of cooperation and coordination which the European Competition Network incorporates if policy learning from the European Community is desirable.