The transatlantic dispute over genetically modified organisms (G.M.O.s) has brought into conflict the United States and the European Union, two long-time allies and economically interdependent democracies with a long record of successful cooperation. Yet the dispute - pitting a largely acceptant U.S. against an E.U. deeply suspicious of G.M.O.s - has developed into one of the most bitter and intractable transatlantic and global conflicts, resisting efforts at negotiated resolution and resulting in a bitterly contested legal battle before the World Trade Organization. Professors Pollack and Shaffer investigate the obstacles to reconciling regulatory differences among nations through international cooperation, through the lens of the G.M.O. dispute. The book addresses the dynamic interactions of domestic law and politics, transnational networks, international regimes, and global markets, through a theoretically grounded and empirically comprehensive analysis of the governance of G.M. foods and crops. They demonstrate that the deeply politicized, entrenched and path-dependent nature of the regulation of G.M.O.s in the U.S. and the E.U. has fundamentally shaped negotiations and decision-making at the international level, limiting the prospects for deliberation and providing incentives for both sides to engage in hard bargaining and to "shop" for favorable international forums. They then assess the impacts, and the limits, of international pressures on domestic U.S. and European law, politics and business practice, which have remained strikingly resistant to change. International cooperation in areas like G.M.O. regulation, the authors conclude, must overcome multiple obstacles, legal and political, domestic and international. Any effective response to this persistent dispute, they argue, must recognize both the obstacles to successful cooperation, and the options that remain for each side when cooperation fails.