A framework was devised for policy-makers to assess direct bilateral cap-and-trade linkages. A systematic analysis of the economic, political and regulatory implications indicates potential benefits along with a number of potentially negative side-effects. Theoretically, economic benefits are expected from quasi-static short-term and dynamic efficiency gains. However, a careful review of these arguments indicates that, due to the presence of market distortions or terms-of-trade effects, international emissions trading may not be welfare-enhancing for all countries. Political benefits are derived from the reinforced commitment to international climate policy and the elimination of competitiveness concerns among linking partners, but this must be weighed against the possible incentive to adjust national caps in anticipation of linking. Regulatory disadvantages may arise from the linked system's inconsistency with original domestic policy objectives, and from the partial de facto cession of discretionary control over the domestic emissions trading system. Finally, as an illustration, a link between the EU ETS and a prospective US trading system is assessed, and the major trade-offs identified.
