Abstract
This paper suggests a novel mechanism behind issue linkage in international relations: As the scope of an issue area expands, touching upon an increasing number of policies, previously uninterested actors mobilize due to worries of interference. These actors seek carve-outs from new rules, and attempt to exert more direct influence on the expanding issue area. To demonstrate this mechanism, I focus on the example of trade and environmental policy, where political linkages have risen sharply since the 1990s. Drawing on historical evidence from the U.S. and interviews in Europe, I show that environmental groups have been important drivers of the emerging political linkage. These groups mobilized when trade policy expanded in scope, out of a perception of threat. In addition, quantitative analysis of PTA content finds that the presence of environmental civil society groups is positively associated with environmental clauses and that this relationship is moderated by agreements' economic scope
