Wen-jen Hsieh: This paper is an interesting study of non-tariff measures (NTMs), and it provides a broad overview on the topic with the aim of providing a practical way forward for the improvement of NTMs in ASEAN. The authors deal with myriad approaches. First, they provide an introduction to the definition, justification, and specificities of NTMs, as differentiated from tariff and non-tariff barriers (the latter being a subset of NTMs), which, unlike NTMs, have a protectionist purpose.

The article then discusses the difficulties in generating and obtaining data about NTMs and the present efforts by supranational institutions to generate official, objective data at national level.

The next section uses available data to provide an overview of NTM coverage worldwide, and this provides some interesting, counterintuitive features—namely, that NTMs are more widely used in developing countries where the capacity to implement them is more limited. An empirical model is then developed to estimate NTM values for ASEAN countries and the data thus obtained compared with countries that are considered to implement “international best practices”, mainly because they use Regulatory Impact Assessment to evaluate their frameworks. The authors find that both incidence and severity of NTM effects on trade in ASEAN are moderate compared with other countries, and not too far from middle-income best practice countries, although further from developed ones.

The core contribution of the paper lies in the recommendation for streamlining NTMs in ASEAN. For this they present first global (at WTO) and regional (as in East Africa) efforts at adjusting NTMs to the intended purposes while eliminating protectionist bias in the regulatory framework. The authors acknowledge the difficulty in obtaining results through a traditional notify-negotiate-eliminate approach on a multilateral basis; they present a case of country-level reform in Mexico. Although this process did not deliver optimal results, the authors conclude that it is the best approach possible, and they present a model for country-level reform in ASEAN.

The paper is overall educational and interesting. It provides a great overview of the NTM issue. In fact, the material in the text could provide for two or even three separate articles.

The background explanation and empirical analysis are somehow not fully necessary for the latter discussion on measures to improve NTMs in ASEAN. Furthermore, the conclusions showing that NTMs impact on ASEAN is not far from international best practices could even eliminate the necessity of the latter discussion on regulatory reform. Developing countries could put scarce public resources to better use in solving more acute problems if this issue is yet within tolerable levels. Particularly so when, as argued repeatedly by the authors, said regulations have legitimate purposes such as consumer and environmental protection, which make them non-superfluous.

This also relates to the great length of the article, which winds up being an analysis that is partially empirical with positive or normative analysis. It is not fully clear whether it is a world overview or a regional and comparative analysis because the issues analyzed in Sections 2 and 3 are not fully consistent, giving a priority to income-based comparisons at the world level that are not present when analyzing ASEAN.

The article does a good job at presenting NTMs and their contrast with trade barriers, although there are no references to academic discussions on the matter and a connection with past work or official materials on the topic that would be of interest.

It is also worth noting that the authors consider that ad valorem equivalents (AVEs) are only obtainable as cross-country averages with a “country-specific flavor” at best, whereas later they claim that their empirical model provides “country-specific” data based on the same premises, which probably calls for precaution when interpreting the data about the severity of NTMs in ASEAN.

In methodological terms, a concern arises about the treatment of the EU. The text suggests that it has been treated as a single country at least in the calculation of AVEs. It should be clarified if this is so for the whole article and if such is the case ensure that treatment of the EU as individual countries would not change the conclusions. This is particularly relevant for Section 2, where a number of additional cases of high-income, high-coverage countries could tilt the correlation found between these two factors differently than is shown in Figure 3.

If the correlation persists, it needs to be acknowledged that the sample still covers barely half of the world's countries and how this could affect the findings.

In studying the qualitative reasons for the counterintuitive result, it would also be useful to address the potential differences in actual implementation of the rules as well as the differences in productive structures that may explain certain regulatory choices.

In sum, the article is a well-written, in-depth analysis that provides a useful addition to the existing literature and, furthermore, suggests adjusted practical solutions to the problem of minimizing trade distortion by NTMs and the elimination of trade barriers. I enjoyed reading the paper and would suggest developing a series of papers delving into its different facets.