PHASING IN AND PHASING OUT PROTECTIONISM WITH COSTLY ADJUSTMENTS OF LABOUR
研究劳动力跨部门调整成本高昂时最优贸易政策的动态路径，发现政府若能承诺未来政策，最优路径是先逐步引入再退出对衰退行业的保护，而非渐进自由化；若无承诺能力，则一开始就维持自由贸易。
We study the dynamics of optimal trade policy in a model with costly inter-sectoral adjustment of labour, where migrants pay less than the marginal social cost of migration. If workers have rational expectations, a future tariff has an announcement effect on the current migration decision. If the government is able to commit itself to future policy, the optimal trajectory involves phasing in and then phasing out protection of the dying sector. This contrasts with recommendations of gradual liberalization. Without the ability to make commitments, the equilibrium policy begins with and maintains free trade.