Table 5, while some countries certainly use TTBs more than others, the overall country-level pattern is not as clear as the import tariffs covered in Section 2.1. First, significant users of TTBs include a mix of high-income (US, EU) and emerging (Argentina, Brazil, China, India, Mexico, and Turkey) economies; many of the emerging economies only began using TTBs in the late 1980s or early 1990s. Second, not all WTO members use TTBs.<sup>52</sup> Most of the poorest developing countries in our sample do not use TTBs, and thus are not listed. While most of the high-income and emerging economies have become users of TTBs over time - albeit at different levels and frequencies - there are some high-income economies which only rarely apply them. For example, Japan is a rare user even though its antidumping law dates to 1920. Furthermore, there are some countries - e.g., Australia, Canada, and even South Africa - who were major users of TTBs historically but whose use during 1995-2013 has declined relative to earlier decades. Finally, customs union partner pairs that share a common applied MFN tariff - e.g., EU-Turkey, Argentina-Brazil - retain the legal authority to implement their TTB policies independently and clearly do so.

Before moving on to our next question of interest, we pause briefly to note that the composition of antidumping, safeguards and countervailing duties used by different countries is not systematic. While the United States has implemented each of the three major TTB policies with a significant share of import coverage during this period, most of the TTB users tend to rely primarily on antidumping, with a more limited use of safeguards.<sup>53</sup> Countervailing duty laws, on the other hand, have only recently been adopted by a number of economies and are only starting to be implemented; as such, their import coverage has been fairly limited to high-income economies including the US, EU and Canada. The China-specific transitional safeguard mechanism that was introduced as part of China’s WTO Accession Protocol in 2001 has not been frequently utilized.<sup>54</sup> Next, do countries make significant changes to the levels of their TTB import protection over time? Figure 10 presents a measure of the time path of TTB use for the EU, US, China and India over a slightly longer time period of 1990-2013. The figure plots four series of data - for all TTB policies (and antidumping only), a ‘flow’ measure of the share of HS06 import products each year subject to a newly-initiated TTB investigation that could result in a new import restriction; and for all TTB policies (and antidumping only), a ‘stock’ measure of the share of HS06 import products

> 52The table lists the data for the users of the policies that are ‘known’ users; users are known even if detailed data on their use is not available from Bown (2014a) due to the WTO’s minimum reporting requirements. Countries are listed if they are known users of the policy even if the details of the data on their policy use are not available (‘na’). For an exploratory analysis of why countries adopt antidumping laws, for example, see Vandenbussche and Zanardi (2008).

> 53Significant users of safeguards in our sample of economies, for example, include Argentina, Brazil, Egypt, the EU, China, India, Indonesia, and Turkey - though for the US, EU, and China, the significant safeguards use during this period was dominated by the almost simultaneous safeguards imposed over an overlapping set of steel products in 2001-2003. For a discussion of the US safeguard on steel, and a comparison to the similarities on prior US use of antidumping and countervailing duties products during the 1990-2003 period, see Bown (2013a). On the other hand, Blonigen et al. (2013) use the US steel industry to examine the nonequivalent market power effects of quotas and tariffs arising in the industry, some of which arose through TTB policies.

> 54Notwithstanding the somewhat infamous use of this policy by the US on imports of tires in 2009, the peak use was by Colombia, briefly, over a set of textile and apparel products in 2005. For a discussion of the US safeguard on tires, see Charnovitz and Hoekman (2013). For the China safeguard more broadly, see Bown (2010) and Bown and Crowley (2010).

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