Why negotiate a legally binding mercury convention?

The purpose of this paper is to explain how and why consensus was reached on a legally binding approach given the opposition of powerful actors. Why did the United States and key emerging economies change their positions? We apply tools from the regime formation literature—classical perspectives on power, interests and knowledge—and the use of different leadership tools to shed light on the issue. Knowledge-based intellectual leadership was exercised by the UNEP Secretariat, providing new information on the seriousness and scope of the problem. Power-based leadership through unilateral action was provided by the United States. When the United States changed position after change in domestic leadership, political costs increased for other opponents. Finally, interest-based instrumental leadership was provided by many proponents, with UNEP and among others the EU in the lead. Still, conflicts remain on control measures and the form of financial mechanism. Copyright Springer Science+Business Media Dordrecht 2013