Federal states, such as Canada and the United States, face unique problems in implementing international agreements because they require the acceptance by subnational governments of these treaties even when the negotiations (i) do not involve them and (ii) may be impeding the rights of those subnational governments. Ever since the "watertight compartments" decision of Lord Atkin in the 1937 Labour Standards case, provincial autonomy within its sphere of influence has been a primary foci of Canadian jurisprudence. The primacy of provincial legislatures in the respective realms means that international obligations cannot be forced on them without their consent. On the other hand, both the interstate commerce clause of the US Constitution and the federal power to make treaties has been interpreted broadly to prohibit state interference in US government-signed international treaties. Even non-federal states such as the People's Republic of China have had to deal with this problem given the Special Administrative Regions of Hong Kong and Macau and the SARs' ability to sign international agreements without PRC involvement. This issue even affects sovereign states such as Jamaica when they are part of a common market superstructure, such as the proposed Caribbean Common Market (CARICOM). This paper examines, using examples drawn from Canada, the United States, Hong Kong, and the Caribbean, the influence subnational governments (and sovereign governments that are part of a common market) have on the viability of international agreements and uses game theory to suggest ways to balance the need to avoid subnational sabotage of such agreements without invoking a national paramountcy argument that could destroy a country's federal structure and create irreparable harm to the rights of subnational governments.