Federation
Federation is defined by Professor E. A. Freeman as "any union of States stronger than mere alliance, but whose members enjoy more than merely municipal freedom." Federations in this wide sense are either confederations (the states composing which retain their full sovereignty, but are in permanent alliance) or federal unions, in which each state delegates certain of its sovereign powers to a central government, including the management of foreign relations, military and naval matters, certain powers of taxation, e.g. as to levying customs duties, and the right of legislation on certain specified subjects. All powers not specifically delegated remain vested in the governments of the separate states. Thus divorce is very easy in Indiana, but is not recognised at all in South Carolina; but neither state can impose customs duties or adopt a monarchical form of government. Normally, a federal union (to which the term federation is often confined) implies a written federal constitution, and a court or other central authority to expound it. Some external danger which the members could not resist singly, a high degree of similarity, and an approximate equality between all or many of the members, are usually conditions of federation. The Acheean League in antiquity, Switzerland, and the United States, are leading instances of federal republics, the German Empire (which is, however, controlled by Prussia) is a federal monarchy, and many persons hope that the British Empire will one day be a federal union.