Main Act or Side Show? Model Agreements by International Institutions and Their Reuse in Investment Treaty Texts

Scholars and negotiators often assert that model treaty texts published by international institutions (IIs) shape investment treaty design. This paper empirically investigates the reuse of international institutions’ treaty templates. It tracks the imprint of six international institution templates on the text of negotiated international investment agreements (IIAs) using the Electronic Database of Investment Treaties. We find that the overall impact of international institution models has been low. No international investment agreement in our dataset was copied from an international institution’s model wholesale. On average, annual similarity between model texts and negotiated investment treaties is lower than 40% and significantly lower than the influence of international institutions’ models in the structurally similar international tax treaty regime. However, we do find evidence of an impact of international institutions' language on specific salient clauses. For example, the text of key investment protection clauses in the 1967 Draft Convention of the Organization of Economic Cooperation and Development was reproduced in hundreds of international investment agreements and novel clauses on investor responsibility first introduced in the 2006 International Institute for Sustainable Development model have subsequently been copied verbatim into negotiated international investment agreements. Our work concludes by discussing explanations for the comparatively low imprint of international institutions, notes other pathways for these institutions to influence treaty design, and sketches out an agenda for future research.