International human rights instruments can be classified into two categories: declarations, adopted by bodies such as the United Nations General Assembly, which are not legally binding although they may be politically so; and conventions, which are legally binding instruments concluded under international law. International treaties can, over time, obtain the status of customary international law.International human rights instruments can be divided further into global instruments, to which any state in the world can be a party, and regional instruments, which are restricted to states in a particular region of the world.Most conventions establish mechanisms to oversee their implementation. In some cases these mechanisms have relatively little power, and are often ignored by member states; in other cases these mechanisms have great political and legal authority, and their decisions are almost always implemented. Examples of the first case include the UN treaty committees, while the best exemplar of the second case is the European Court of Human Rights.