Learning and the Precision of International Investment Agreements

The international regime for the promotion and protection of foreign investment consists of a multitude of close to 3,000 bilateral investment treaties (BITs) and related international investment agreements (IIAs). Yet, despite a growing body of research on IIAs, scholars in political economy have paid little attention to the legal language in the treaties themselves. In this research note, we draw on the conceptual apparatus of the legalization literature and focus on legal precision in BITs. We use a new data set created through quantitative text analysis to develop an index measuring legal precision. We then investigate the causes of the pronounced increase in precision in BITs and the considerable variation across treaties. We argue that capital-exporting countries are the primary drivers of change, and that they are motivated because they learn the implications of existing legal language from two sources: First, from the growing number of arbitration proceedings, and second, when they themselves are targeted by such claims. We provide statistical tests of our hypotheses and find ample support.