 A federation is one species of such a federal order; other species are unions, confederations, leagues and decentralised unions—and hybrids such as the present European Union (Elazar 1987, Watts 1998). A federation in this sense involves a territorial division of power between constituent units—sometimes called ‘provinces’, ‘cantons’, possibly ‘cities’, or confusingly ‘states’—and a common government. This division of power is typically entrenched in a constitution which neither a member unit nor the common government can alter unilaterally. The member unit and the common government both have direct effect on the citizenry—the common government operates “on the individual citizens composing the nation” (Federalist Paper 39)—and the authorities of both are directly elected (Watts 1998, 121). In comparison, decentralized authority in unitary states can typically be revoked by the central legislature at will. Many multilevel forms of governance may also be revised by units at one level without consent by bodies at other levels. Such entrenchments notwithstanding, some centralization often occurs owing to the constitutional interpretations by a federal level court in charge of settling conflicts regarding the scopes of final legislative and/or judicial authority.