Competence for the development of rules of private international law has become more-and-more centralized in the European Union, while remaining diffused in the United States. Nowhere has this divergence of process in private international law development been clearer than in the approach each has so far taken to the ratification and implementation of the 2005 Hague Convention on Choice of Court Agreements. In Europe, ratification has been preceded by the 2012 Recast of the Brussels I Regulation, coordinating internal and external developments, and reaffirming Union competence for future developments, both internally and externally. In the United States, debate has arisen over whether the Convention should be implemented in a single federal statute – as was done for the New York Convention in the Federal Arbitration Act – or through state-by-state enactment of a Uniform Act promulgated by the National Conference of Commissioners on Uniform State Laws. These differences in approach are important to future negotiations in multilateral fora such as The Hague Conference on Private International law, UNCITRAL, and UNIDROIT. They demonstrate a coherence of approach within the EU which attracts not only its own Member States, but also external constituencies in international negotiations, and diffuse development of the law in the United States, which tends to make leadership in multilateral negotiations difficult.