This text concentrates on the concepts and mechanisms in international law that are relevant to reservations. The role of states, and the possibilities afforded supervisory committees to monitor the impact of reservations, form the other important topic. Little information exists on the impact of reservations to UN human rights instruments. This study highlights the possibilities states and supervisory organs have to reduce the detrimental impact of reservations within the existing framework and gives some proposals for a better and tighter provision on reservations.