Institutions,Forum Shopping,and Trade Disputes 737 complainant because it will be less fearful of being sued by its more liberal multi- lateral trade partners,and a liberal one because it will be less concerned about suing its less liberal multilateral trade partners. Forum shopping has broader implications for studying institutions.First,it sheds light on the rational design literature,notably with respect to its treatment of mem- bership.As Koremonos,Lipson,and Snidal put it,membership "is an endogenous design choice"that can later emerge as an exogenous constraint on the use of an institution.>This is precisely what is happening here,only that,where forum shop- ping is concerned,the issue is how the overlap of two (or more)memberships affects not only the relative use of these institutions (that is,where a case is filed), but whether these institutions are used at all (that is,if a case is filed).Impor- tantly,while some institutions have few rules on overlapping memberships,others formally govern these relationships,including through merger,as examples in Cen- tral Asia and Africa make clear.Thus,the prospect of forum shopping raises ques- tions about how institutions manage overlapping memberships. Second,forum shopping also speaks to more general questions about institu- tional design,notably with respect to the trade-off between"rigidity"and"stabil- ity."Echoing Goldstein and Martin's argument that too much legalization may undermine trade liberalization at the WTO,?Rosendorff explains that institutions need to strike a balance between legalism(that is,rigidity),which aims at further- ing compliance,and flexibility (that is,stability),which helps attract and retain members.s While he looks at the Dispute Settlement Understanding(DSU)in this regard,the fact is that,by allowing forum shopping,the WTO and other institu- tions are also investing in flexibility,giving complainants latitude in deciding where to file cases.This opportunity for forum shopping,like membership,is an endog- enous design choice.For example,it has been hotly debated in drafting a dispute settlement mechanism for the World Intellectual Property Organization,where some members prefer to leave the choice of forum to the complainant,but where most "support the view that 'forum shopping'should not be allowed."Thus,forum shopping is a salient-and often contentious-issue in trying to balance rigidity and stability where memberships overlap. This article proceeds as follows.The first section elaborates the puzzle of forum shopping.The second section develops the argument of this article.The third sec- tion probes the usefulness of the argument in explaining the safeguard and peri- odicals disputes.The fourth section concludes with a discussion of implications for institutional theory. 5.Koremenos,Lipson,and Snidal 2001,777. 6.As I explain below,the Eurasian Economic Community and the Central Asian Cooperation Orga- nization have merged,while the Common Market for Eastern and Southern Africa and the African Economic Community are scheduled to do so. 7.Goldstein and Martin 2000. 8.Rosendorff 2005. 9.World Intellectual Property Organization 1990.complainant because it will be less fearful of being sued by its more liberal multi￾lateral trade partners, and a liberal one because it will be less concerned about suing its less liberal multilateral trade partners+ Forum shopping has broader implications for studying institutions+ First, it sheds light on the rational design literature, notably with respect to its treatment of mem￾bership+ As Koremonos, Lipson, and Snidal put it, membership “is an endogenous design choice” that can later emerge as an exogenous constraint on the use of an institution+ 5 This is precisely what is happening here, only that, where forum shop￾ping is concerned, the issue is how the overlap of two ~or more! memberships affects not only the relative use of these institutions ~that is, where a case is filed!, but whether these institutions are used at all ~that is, if a case is filed!+ Impor￾tantly, while some institutions have few rules on overlapping memberships, others formally govern these relationships, including through merger, as examples in Cen￾tral Asia and Africa make clear+ 6 Thus, the prospect of forum shopping raises ques￾tions about how institutions manage overlapping memberships+ Second, forum shopping also speaks to more general questions about institu￾tional design, notably with respect to the trade-off between “rigidity” and “stabil￾ity+” Echoing Goldstein and Martin’s argument that too much legalization may undermine trade liberalization at the WTO, 7 Rosendorff explains that institutions need to strike a balance between legalism ~that is, rigidity!, which aims at further￾ing compliance, and flexibility ~that is, stability!, which helps attract and retain members+ 8 While he looks at the Dispute Settlement Understanding ~DSU! in this regard, the fact is that, by allowing forum shopping, the WTO and other institu￾tions are also investing in flexibility, giving complainants latitude in deciding where to file cases+ This opportunity for forum shopping, like membership, is an endog￾enous design choice+ For example, it has been hotly debated in drafting a dispute settlement mechanism for the World Intellectual Property Organization, where some members prefer to leave the choice of forum to the complainant, but where most “support the view that ‘forum shopping’ should not be allowed+”9 Thus, forum shopping is a salient—and often contentious—issue in trying to balance rigidity and stability where memberships overlap+ This article proceeds as follows+ The first section elaborates the puzzle of forum shopping+ The second section develops the argument of this article+ The third sec￾tion probes the usefulness of the argument in explaining the safeguard and peri￾odicals disputes+ The fourth section concludes with a discussion of implications for institutional theory+ 5+ Koremenos, Lipson, and Snidal 2001, 777+ 6+ As I explain below, the Eurasian Economic Community and the Central Asian Cooperation Orga￾nization have merged, while the Common Market for Eastern and Southern Africa and the African Economic Community are scheduled to do so+ 7+ Goldstein and Martin 2000+ 8+ Rosendorff 2005+ 9+ World Intellectual Property Organization 1990+ Institutions, Forum Shopping, and Trade Disputes 737