Ecologic analyses within the framework of this project the institutional interactions between international treaty systems and European environmental instruments. Although they are negotiated separately, they affect each others' performance and effectiveness. Such 'institutional interaction' will inevitably cause conflicts if regulatory approaches are incompatible. If approaches are mutually reinforcing, however, it may also create synergies. If not addressed properly, inter-institutional conflicts can inhibit and counteract the effectiveness of international environmental co-operation.