Implementation is at the core of lawmaking in our divided government. A rich literature covers the waterfront with respect to agencies’ implementation of legislative mandates, and another equally robust line of scholarship considers Congress’s implementation of treaties. Missing from those discussions, however, is another area of implementation central to U.S. foreign relations: the implementation of transnational regulatory agreements.

This Article examines how federal agencies have harnessed far-reaching discretion from Congress on whether and how to implement thousands of international agreements. Agencies regularly implement agreements by relying on a self-developed menu of options, much like they do in the domestic regulatory context—only without the checks and balances that those processes provide. This analysis of the operation of agreements presents a set of extemporized means through which the executive maintains control of these agreements and their regulation of the rights of private actors without legislative intervention or administrative law constraints. These revelations stand in contrast with conventional understandings of implementation as well as to prior accounts of how “international law [is] part of our law.”