Master of Arts / Department of Economics / Peri da Silva / Terms-of-trade argument (the optimal tariff theory) refers that a country with market power can gain national welfare when they impose a tariff for foreign exports and generate welfare at the expense of foreign trade partners. This argument has been long-term applied as an assumption in many theoretical trade models. Feenstra (2004) shows that the theoretical optimal tariff is equal to the inverse foreign export supply elasticity which implies if we can get the value of inverse export elasticity for each good then we can set up the optimal tariff to maximized our national welfare. Compared with the development in theory, the progress in the empirical study of terms-of-trade argument has been a bit stagnant until recent years. Christian Broda, Nuno Limão and David Weinstein (2008) show us an important empirical evidence that countries use market power when they set up tariff in their non-cooperative trade policy. And they estimate both import demand elasticity and export supply elasticity at the four-digit Harmonized System level by using 16 countries’ trade data and production data. In this report, we firstly introduce the theoretical basis of optimal tariff. Then we will discuss the contributions of Broda et al (2008) and other economists’ empirical findings of optimal tariff theory which applies Broda, Limão and Weinstein’s estimates of elasticities

Following Devereux, Shi, and Xu（2007）, this thesis analyzes the effects of tariffs and derives the optimal tariff under the circumstances that the US dollar acts as an international ‘vehicle’ currency— all traded goods prices between the US and the rest of the world are set in US dollars. We set a tariff policy rule which allows the authority to react to country-specific productivity shocks. The analysis on the equilibrium shows that the current tariff imposed by the US on its output is expansionary. However, for the rest of the world, a current tariff imposed by the US is contractionary. Optimal tariff under flexible and fixed exchange rates are examined. Under flexible exchange rate, optimal tariff policy parameters of the US are dependent only on the monetary policy of its own being indifferent to the exchange rate movement；the exchange rate movement is crucial to the optimal tariff policy of the rest of the world. Nevertheless, the optimal tariff policy of the US under fixed exchange rate is the same as that under the flexible exchange rate, while the policy of the rest of the world is altered owing to the loss of control on its domestic money supply to do the unilateral peg.

Doctor of Philosophy / Department of Economics / Yang M. Chang / Concerns over the possible loss of government revenue resulting from tariff reductions under trade liberalization have triggered many developing countries to opt for a strategy of raising destination-based consumption taxes on tradable goods. The first essay analyzes the welfare effects of a coordinated tariff reduction and domestic tax reform when the objective of a reforming country is to keep its government revenue unchanged. Assuming imperfect competition in an import-competing industry, we find that revenue-neutral reform involving tariff reduction and an increase in domestic tax rate may reduce domestic welfare under plausible assumptions. It also discusses the scenario in which the reforming country's objective is to keep domestic profit (or production) unchanged. We further identify the conditions under which a profit-neutral tariff and tax reform may be welfare-improving or welfare-deteriorating. The second essay uses a reciprocal-dumping model to examine the welfare effects of the Byrd Amendment (i.e., the Continued Dumping and Subsidy Offset Act, or CDSOA). It analyzes the differences in optimal tariffs set by the home and foreign governments when the home (i.e., the U.S.) government redistributes anti-dumping duties to its domestic firm under the new trade law, as compared to the traditional antidumping policy under which these duties are government revenues. We derive conditions under which the CDSOA may raise or lower the price of an import-competing good in the U.S. market. The results show that the CDSOA is an instrument of protectionism and strictly improves the home country welfare when markets are less competitive than in Cournot equilibrium. We find that under the same market characteristics, the new trade law strictly reduces foreign country welfare. The CDSOA's welfare effect is shown to be ambiguous, however, when markets are more competitive than Cournot. The third essay modifies the model presented in Essay 2 to allow for the scenario in which the foreign country strategically responds to the home country's CDSOA law by adopting similar trade law. The results show that the foreign country is able to enhance its national welfare when the import-competing markets are less competitive than in the Cournot equilibrium. We also discuss whether it is welfare-improving for the U.S. to voluntarily repeal the Byrd Amendment and restore the traditional antidumping policy, considering that, otherwise, its trading partner may also adopt the CDSOA law. We find that it is still in the best interest to the U.S. not to revoke the Byrd Amendment when markets are less competitive than Cournot. When markets are more competitive than Cournot, however, repealing the Amendment may turn out to be socially welfare-improving.