important research questions in this area.<sup>131</sup> For example, legal scholars now parse the language of each newly-arriving WTO legal decision – so as to draw potential precedent implications for international and domestic law, as well as for public policy –with the same voracity as the American bar devours fresh Supreme Court rulings or Europeans tackle judgments from the European Court of Justice. Furthermore, legal and economic scholars have already teamed for more than a decade to annually publish joint inter-disciplinary assessments of each year’s new WTO jurisprudence.<sup>132</sup> We begin this section by describing how the WTO dispute settlement system has been used to date. We then survey the theory on the role of the WTO dispute settlement system before examining the relationship between PTA implementation and WTO dispute settlement activity. We also describe recent PTA disputes associated with the enforcement of non-trade policies. Finally, we conclude with thoughts on the relative merits of a multilateral dispute settlement system.

# 7.1 WTO Dispute Settlement: Patterns in Use

WTO disputes involve state-to-state level interaction. Here we characterize some of the data on the nearly 500 formal disputes initiated between 1995 and 2014 in order to ...rst clarify what the disputes tend to be about, who they tend to be between, how the process works, and the typical outcomes that arise. Due to a number of potential issues related to sample selection, a central argument of the literature described below is that dispute settlement cannot be appreciated or evaluated based solely on an appeal to information regarding the disputes that are observed –i.e., the procedures also have important “o¤ equilibrium” implications that do not necessarily arise through formal disputes. Nevertheless, evidence that the WTO members are putting trust in the system by frequently triggering its use over important policies or signi...cant amounts of trade is potentially supportive of the idea that dispute settlement is playing a signi...cant role.<sup>133</sup>

## 7.1.1 WTO disputes are most frequently allegations of excessive import protection

We begin by appealing to an assessment drawn from a database of WTO dispute settlement information compiled and made publicly available by Horn and Mavroidis (2011). Of the formal disputes that have arisen to date, the typical topic concerns a plainti¤ (“complainant”) member alleging that the defendant (“respondent”) country has imposed an excessive level of import protection.

Horn, Johannesson, and Mavroidis (2011) examine disputes taking place between 1995 and 2010 and report that nearly 95 percent of all WTO disputes concern trade in goods, with the remainder

> 131 Examples of seminal legal scholarship over GATT law begin with Dam (1970), Jackson (1969) and Hudec (1990). The WTO’s legal process is explained in more detail by Palmeter and Mavroidis (2004). Davis (2012) provides a recent overview of political science research on WTO dispute settlement.

> 132 Beginning in 2001, Horn and Mavroidis (2003) initiated a series of annual assessments with the backing of the American Law Institute, subsequently extended by Bown and Mavroidis (2013), which pairs legal scholars with economists to jointly analyze each of the formal WTO Appellate Body (and non-appealed Panel) decisions that arise. Cumulatively these legal-economic assessments have covered nearly 100 di¤erent individual dispute decisions to date.

> 133 Put di¤erently, at this moment in time, the WTO members do not seem to be avoiding use of the system or clamoring to develop an alternative system. The GATT experience of the 1980s in particular suggests that that is not necessarily always the case (Bhagwati and Hudec, 1990).

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