Subsidiarity is perhaps presently best known as a general principle of European Union law. According to this principle, the Union may only act (i.e. make laws) collectively where independent action of individual countries is insufficient without equal action by other members. The principle was established in the 1992 Treaty of Maastricht. However, at the local level it was already a key element of the European Charter of Local Self-Government, an instrument of the Council of Europe promulgated in 1985 (see Article 4, Paragraph 3 of the Charter) (which states that the exercise of public responsibilities should be decentralised). Subsidiarity is related in essence to, but should not be confused with, the concept of a margin of appreciation.