The United States is an outlier with respect to the Kyoto Protocol; it has neither ratified the protocol nor abided by its terms. The follow-up protocol to Kyoto will presumably also have its outliers. In this Essay, I will explain why outliers will be of critical importance to the next climate accord. I will also explain why the importance of outliers, in turn, will make the treatment of outliers practically difficult. I will also touch upon some issues that may arise to the extent that the next accord seeks to use trade sanctions as a means of punishing outliers. I will not endeavor to cover all aspects of these questions; instead, I hope to contribute to the dialogue by highlighting points that I believe to be most salient. 

Part I of the Essay sets out the problem of climate change, and the international community’s responses to it, including the Kyoto Protocol. It explains how climate change differs from other environmental challenges to which the international community has responded. Part II looks at treaty outliers; it examines the possible characteristics of outliers to a post-Kyoto protocol. It also outlines different approaches that a post-Kyoto protocol might take with respect to outliers. It then elucidates, in particular, issues that might arise from the attempt to use trade sanctions.