Competition policy is one important aspect of trade liberalization. However, when examining preferential trade agreements (PTAs), a major type of policy tools to liberalize trade, competition provisions are revealed not to be uniformly distributed across these treaties. What explains the variation in the design of competition clauses in PTAs? Borrowing insights from the rational design of international institutions and combining them with those from treaty ratification and policy diffusion literatures, I identify five major causal mechanisms through which competition provisions are incorporated into PTAs. In evaluating them, I employ a range of operationalization techniques to capture the proposed mechanisms. A treaty-level analysis of 319 PTAs over the period 1960–2015 lends strong and robust support to most of the hypothesized relationships. By integrating theoretical frameworks across international political economy literatures with that from law and economics scholarship, this study demonstrates the utility of political science thinking to the real-world international law-making.
