A defining feature of the European acid rain case, and the 1994 Sulphur Protocol in particular, is the reliance on formal analysis and integrated assessment modeling. In this chapter, different analytical methods

that contributed to the policy success story are compared. What types of information were useful to negotiators in providing the groundwork for consensus? What types of information were less useful, and why? In this international context, where the negotiations were more complex and the issues broader than in many local contexts, negotiators succeeded when they narrowed the problem frame significantly. Achieving consensus may also have been related to the narrow focus of negotiators on “bright lines,” or apparently natural targets for pollution control, rather than on more ambiguous targets that required consensus on human values. A comparison of the transnational negotiation process with the process of reducing the same pollutants at the local level indicates that bright lines, informed by natural science rather than economic balancing, were far more influential in the transboundary context, whereas balancing approaches were more attractive at the local level.