Overlapping institutions, forum shopping, and dispute settlement in international trade

Preferential trade agreements offer members an alternative to dispute settlement at the World Trade Organization. This gives rise to forum shopping, in that complainants can file regionally, multilaterally, or not at all. What explains this choice of forum? I argue that complainants strategically discriminate among overlapping memberships: on a given measure(s), some prefer to set a precedent that bears only on a subset of their trade relations, others a precedent that bears on all their trade relations, while still others prefer not to set a precedent. Thus, the key to forum shopping is not simply which institution is likely to come closest to the complainant's ideal ruling against the defendant, but where the resulting precedent will be more useful in the future, enabling the complainant to bring litigation against other members, rather than helping other members bring litigation against the complainant. I consider disputes over Mexican brooms and Canadian periodicals.