mode of political organization that unites separate states or other polities within an overarching political system in such a way as to allow each to maintain its own fundamental political integrity. Federal systems do this by requiring that basic policies be made and implemented through negotiation in some form, so that all the members can share in making and executing decisions. The political principles that animate federal systems emphasize the primacy of bargaining and negotiated coordination among several power centres; they stress the virtues of dispersed power centres as a means for safeguarding individual and local liberties.

The various political systems that call themselves federal differ in many ways. Certain characteristics and principles, however, are common to all truly federal systems.

First, the federal relationship must be established or confirmed through a perpetual covenant of union, usually embodied in a written constitution that outlines the terms by which power is divided or shared; the constitution can be altered only by extraordinary procedures. These constitutions are distinctive in being not simply compacts between rulers and ruled but involving the people, the general government, and the states constituting the federal union. The constituent states, moreover, often retain constitution-making rights of their own.

Second, the political system itself must reflect the constitution by actually diffusing power among a number of substantially self-sustaining centres. Such a diffusion of power may be termed noncentralization. Noncentralization is a way of ensuring in practice that the authority to participate in exercising political power (power, balance of) cannot be taken away from the general or the state governments without common consent.

A third element of any federal system is what has been called in the United States territorial democracy. This has two faces: the use of areal divisions to ensure neutrality and equality in the representation of the various groups and interests in the polity and the use of such divisions to secure local autonomy and representation for diverse groups within the same civil society. Territorial neutrality has proved highly useful in societies that are changing, allowing for the representation of new interests in proportion to their strength simply by allowing their supporters to vote in relatively equal territorial units. At the same time, the accommodation of very diverse groups whose differences are fundamental rather than transient by giving them territorial power bases of their own has enhanced the ability of federal systems to function as vehicles of political integration while preserving democratic government. One example of this system may be seen in Canada, which includes a population of French descent, centred in the province of Quebec.

Modern federal systems generally provide direct lines of communication between the citizenry and all the governments that serve them. The people may and usually do elect representatives to all the governments, and all of them may and usually do administer programs that directly serve the individual citizen.

The existence of those direct lines of communication is one of the features distinguishing federations from leagues or confederations. It is usually based on a sense of common nationality binding the constituent polities and people together. In some countries this sense of nationality has been inherited, as in Germany, while in the United States, Argentina, and Australia it had to be at least partly invented. Canada and Switzerland have had to evolve this sense in order to hold together strongly divergent nationality groups. In the newly formed federal systems of India, Malaysia, and Nigeria, the future of federalism is endangered by the absence of such a common national sense.

Geographic necessity has played a part in promoting the maintenance of union within federal systems. The Mississippi Valley in the United States, the Alps in Switzerland, the island character of the Australian continent, and the mountains and jungles surrounding Brazil have all been influences promoting unity; so have the pressures for Canadian union arising from that country's situation on the border of the United States and the pressures upon the German states generated by their neighbours to the east and west. In this connection, the necessity for a common defense against common enemies has stimulated federal union in the first place and acted to maintain it.

Elements maintaining noncentralization. The constituent polities in a federal system must be fairly equal in population and wealth or else balanced geographically or numerically in their inequalities. In the United States, each geographic section has included both great and small states. In Canada, the ethnic differences between the two largest and richest provinces have prevented them from combining against the others. Swiss federalism has been supported by the existence of groups of cantons of different size categories and religiolinguistic backgrounds. Similar distributions exist in every other successful federal system.

A major reason for the failure of federal systems has often been a lack of balance among the constituent polities. In the German federal empire of the late 19th century, Prussia was so dominant that the other states had little opportunity to provide national leadership or even a reasonably strong alternative to the policy of the king and government. During the Soviet era (1917–90/91), the existence of the Russian Soviet Federated Socialist Republic—occupying three-fourths of the area and containing three-fifths of the population—severely limited the possibility of authentic federal relationships in that country even if the Communist system had not.

Successful federal systems have also been characterized by the permanence of their internal boundaries. Boundary changes may occur, but such changes are made only with the consent of the polities involved and are avoided except in extreme situations.

In a few very important cases, noncentralization is given support through the constitutionally guaranteed existence of different systems of law in the constituent polities. In the United States, each state's legal system stems directly and to a certain extent uniquely from English (and, in one case, French) law, while federal law occupies only an interstitial position binding the systems of the 50 states together. The resulting mixture of laws keeps the administration of justice substantially noncentralized, even in federal courts. In Canada, the existence of common-law and civil-law systems side by side has contributed to French-Canadian cultural survival. Federal systems more often provide for modification of national legal codes by the subnational governments to meet special local needs, as in Switzerland.

The point has often been made that in a truly federal system the constituent polities must have substantial influence over the formal or informal constitutional-amending process. Since constitutional changes are often made without formal constitutional amendment, the position of the constituent polities must be such that serious changes in the political order can be made only by the decision of dispersed majorities that reflect the areal division of powers. Federal theorists have argued that this is important for popular government as well as for federalism.

Noncentralization is also strengthened by giving the constituent polities guaranteed representation in the national legislature and often by giving them a guaranteed role in the national political process. The latter is guaranteed in the written constitutions of the United States and Switzerland. In other systems, such as those of Canada and Latin America, the constituent polities have acquired certain powers of participation, and these have become part of the unwritten constitution.

Perhaps the most important single element in the maintenance of federal noncentralization is the existence of a noncentralized party system. Noncentralized parties initially develop out of the constitutional arrangements of the federal compact, but once they have come into existence they tend to be self-perpetuating and to function as decentralizing forces in their own right. The United States and Canada provide examples of the forms that a noncentralized party system may take. In the two-party system of the United States, the parties are actually coalitions of the state parties (which may in turn be dominated by specific local party organizations) and function as national units only for the quadrennial presidential elections or for purposes of organizing the national Congress. Party financing and decision making are dispersed either among the state organizations or among widely divergent nationwide factions.

In Canada, on the other hand, the parliamentary form of government, with its requirements of party responsibility, means that on the national plane considerably more party cohesiveness must be maintained simply in order to gain and hold power. There has been a fragmentation of the parties along regional or provincial lines. The party victorious in national elections is likely to be the one able to expand its provincial electoral bases temporarily to national proportions.

Federal nations with less-developed party systems frequently gain some of the same decentralizing effects through what the Latin Americans call caudillismo—in which power is diffused among strong local leaders operating in the constituent polities. Caudillistic noncentralization apparently exists also in Nigeria and Malaysia.

Elements maintaining the federal principle. Several devices found in federal systems serve to maintain the federal principle itself. Two of these are of particular importance.

The maintenance of federalism requires that the nation and its constituent polities each have substantially complete governing institutions of their own, with the right to modify those institutions unilaterally within limits set by the compact. Both separate legislative and separate administrative institutions are necessary.

The contractual sharing of public responsibilities by all governments in the system appears to be a central characteristic of federalism. Sharing, broadly conceived, includes common involvement in policy making, financing, and administration. Sharing may be formal or informal; in federal systems, it is usually contractual. The contract is used as a legal device to enable governments to engage in joint action while remaining independent entities. Even where there is no formal arrangement, the spirit of federalism tends to infuse a sense of contractual obligation.

Federal systems or systems strongly influenced by federal principles have been among the most stable and long-lasting of polities. But the successful operation of federal systems requires a particular kind of political environment, one that is conducive to popular government and has the requisite traditions of political cooperation and self-restraint. Beyond this, federal systems operate best in societies with sufficient homogeneity of fundamental interests to allow a great deal of latitude to local government and to permit reliance upon voluntary collaboration. The use of force to maintain domestic order is even more inimical to the successful maintenance of federal patterns of government than to other forms of popular government. Federal systems are most successful in societies that have the human resources to fill many public offices competently and the material resources to afford a measure of economic waste as part of the price of liberty.