Over the past twenty years, major international and regional treaties dedicated to fighting corruption were adopted. However, the precise impact of these instruments is unclear. By ratifying anticorruption treaties, states make an explicit and legally binding commitment to abide by and give effect to the normative principles espoused in them. Yet, there is no guarantee that states will institute the legal measures necessary to comply with their international obligations, especially because the institutional characteristics, monitoring mechanisms and substantive content of these treaties vary greatly. The proposed paper argues that we can actually measure the impact of international or regional anticorruption treaties if they are coupled with review mechanisms that evaluate state compliance with the treaty obligations. The paper looks at the peer review mechanism that was established in 1999 by the Council of Europe (CoE), namely the Group of States against Corruption (GRECO). GRECO's peer review mechanism is based on evaluation and compliance reports, which contain recommendations to the 49 countries under review in order to improve their level of compliance with the provisions under consideration. On the basis of this material, an International Anticorruption Compliance Index (IACI) is developed, which provides a novel way of measuring compliance and at the same time aims at explaining the variation in the anticorruption policies and performance across the countries covered by GRECO reports.
