A Federation is always characterised by the following essential features:
1. Division of Powers:
Division of powers between the central government on the one hand and the state/unit governments on the other is an absolutely essential condition of a federation. In it one part of the authority and power of the state is vested with the central government and the rest is vested with the state governments. Each works within a definite and defined sphere of functions.
There can be different ways in which the division of powers between the centre and states is effected by different federal constitutions. As for example, the US Constitution specifies the powers of the federal government and vests the rest with the state governments, while the Constitution of India defines separately the powers of the union (federal government), powers of the states and concurrent powers which are available in common to both the union and the states, and vests the residuary powers with the union. As such the mode of division of powers can be different but it has to be essentially affected in every federal state. It is the sign post of a federation.
2. Written Constitution:
Since in a federal constitution there is to be affected a division of powers, it becomes essential to effect it in writing in order to make it definite and binding upon both the centre and the states. As such a written constitution is a must for a federation. The constitution is a the deliberate and conscious act of political construction. It must be a written and enacted constitution only then can it affect the division of powers in a clear and efficient way.
3. Rigid Constitution:
A federal constitution has also to be a rigid constitution because it is to be kept immune from unilateral amendment efforts on part of The Centre Government or states. Only the central government and the state governments together can have the power to amend the constitution. Further, in order to maintain stability of the federal organisation, there is prescribed a special method of making the amendments in the constitution.
4. Supremacy of the Constitution:
In a federation the constitution is the supreme law of land. Both the central government and the state governments derive their powers from the constitution. They always work within their own spheres as demarcated by the constitution. No one can violate the provisions of the constitution.
5. Special Role of the Judiciary:
For protecting the supremacy of the constitution. Such a judiciary also essential for performing the role of an arbiter of disputes between the centre and states or among the state governments in respect of their areas of action and power.
The working of a federation always involves the possibility of rise of disputes of jurisdiction between the centre and state governments and here there must be present an umpire, a superior organisation capable of settling these disputes. An independent judiciary armed with the power of interpreting the constitution and of regular such central and state laws as are found to be against the letter and spirit of the constitution, is an essential condition of a federation.
6. Dual Administration:
A federation is characterised by dual administration— one, uniform administration of the central government for all the people of the federation and the other state administrations which are run by the governments of federating units and which differ from state to state or region to region. Each citizen has to obey two sets of law—the central laws and the laws of the state of which he is the resident.
7. Dual Citizenship:
In an ideal federation, each individual gets a double citizenship—one common uniform citizenship of the whole state (Federation) and the second of the province or state of which he is the resident. In the United States, each individual enjoys both the citizenship of the United States as well as of the state of which he is the native resident.
8. Bicameral Legislature:
In a federation, the legislature of the federal government is made a bicameral legislature. In one house the people of the federation are given representation while in the other house the units of the federation are given representation on the basis of equality.
In the United States, the people of the country have been given representation in the House of Representatives and the fifty states of the US federation have been given equal representation, two seats to each state, whether big or small, in the upper house i.e. the Senate. The same is the case in Switzerland.
9. Equality of all Federating States:
One of the key underlying principle of the federation is to treat all states/units of the federation equal, without any consideration for the differences in their size, population and resources. It is because of this requirement that all states are given equal seats in one of the two houses of the central legislature and each enjoys equal rights and autonomy.
These are the essential features of a federation. Any state which has all these features can be legitimately described as a federation.