Conditions for Selecting International Environmental Regimes : The U.S. and the G20 regime on Marine Plastic Litter

Marine Plastic Litter (MPL) has become one of the most important agendas of international environmental policy. Research on international cooperation is required, focusing on countries that are heavily involved in environmental pollution (“major contributing countries.”). However, previous research has not fully described the function of variables that influence a country’s decision to join international environmental regimes. To address this problem, this article will conduct a case study of the U.S. decision, which rejected the Ocean Plastics Charter but joined the Osaka Blue Ocean Vision and the G20 Implementation Framework for Actions on Marine Plastic Litter, by analyzing the following question: “why did the U.S., as a major contributing country in the field of MPL, decided to join the G20 regime but rejected the G7 regime on MPL?” This question will be discussed through two perspectives: (1) differences between the G7 regime and the G20 regime on MPL and (2) the U.S. stance on MPL under the Trump administration. This article concludes that the two variables: (1) involvement of other major contributing countries, and (2) flexibility of policy approaches, function as conditions for the decision of a major contributing country about whether or not to join an international environmental regime.