to address empirically some of our chapter’s main questions. For the temporary trade barrier policies, we examine cross-country differences in the import coverage of these barriers. Within countries, we examine sectoral differences in import protection under these policies and compare sectors with temporary trade barriers to those with high applied tariffs. Furthermore, the levels of these barriers change considerably over time. Finally, they exhibit significant discrimination across trading partners.

Before turning to a description of the policies, we note that, collectively, these non-tariff border policies have been the focus of seminal empirical studies of theories of trade policy determination. Indeed, the modern literature on endogenous import protection focused on these non-tariff policies because the _negotiated_ (MFN) import tariffs (described in Section 2) that the major GATT/WTO members applied were inappropriate for studies of optimal, unconstrained policymaking behavior. Many of the policy instruments described next (and perhaps some from Section 5, below) are important components of the measures of ‘trade policy’ - frequently defined as sector-level coverage ratios - used in Trefler (1993), Goldberg and Maggi (1999), and Gawande and Bandyopadhyay (2000).<sup>47</sup>

# **3.1 Temporary trade barriers of antidumping, countervailing duties, and safeguards**

The first set of trade policy instruments that we consider are antidumping, countervailing duties, and safeguards. These are collectively referred to as temporary trade barriers (TTBs) based on the common property that legally each has a temporary life span. Below we assess both their collective use - motivated by evidence of how they have been used as substitute policy instruments - and we also disentangle their individual use in order to show their relative importance, since the GATT/WTO does impose distinct legal conditions under which use of each can be permitted. While all three require evidence of injury to the domestic, import-competing industry, antidumping also requires evidence that this was caused by low-priced (‘dumped’) imports, countervailing duties require evidence that this was caused by foreign-government subsidized imports, and safeguards require evidence that injury was caused by an unexpected import surge.<sup>48</sup> Overall, according to metrics such as frequency of use and import coverage, the most empirically important of the policies is antidumping. Nevertheless, safeguards use has been important for certain countries and especially during certain periods, and there is also some evidence that countervailing duty use may be increasing for some countries over time.

The data on TTBs is sufficiently comprehensive - at least relative to the other border policies we examine in Section 3 - that we are also able to present measures that illustrate policy variation and thus which can address some of our chapter’s main questions.<sup>49</sup>

> 47More recent research has utilized these data for other purposes, including studies such as Broda, Lim ̃ao and Weinstein (2008) and Blanchard, Bown and Johnson (2016)), so as to validate their primary results (that focus on determinants of applied tariffs) with empirical analysis of other border barriers.

> 48For a comprehensive survey of economics research on antidumping, see Blonigen and Prusa (forthcoming); on countervailing duties and subsidies, see Lee (forthcoming); and on safeguards, see Beshkar and Bond (forthcoming).

> 49The empirical analysis in this section updates and extends much of the information initially presented in

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