Accession Rules for International Institutions

Abstract

Powerful states often accept unanimity voting on accession to international institutions, even though this enables weak states to blackmail powerful states into providing costly side payments. Whereas the literature attributes this choice mainly to efforts to bolster the legitimacy of international institutions, the authors demonstrate that the choice of unanimity also has a strategic component. The authors formally show that unanimous accession rules can profit powerful states by creating uncertainty as to the minimal level of reform that enables accession. If accession is valuable enough and the membership candidate is uncertain about the resolve of weak states, it plays safe by implementing ambitious reforms that improve the efficacy of the international institution. In this case, a legitimacy-efficacy trade-off does not exist: the unanimity rule enhances legitimacy while allowing powerful states to induce significant reforms by applicants to the benefit of current members.