A unitary government is one in which all the powers are vested in the national government and the regional governments. A federal government, on the other hand, is one in which powers are divided between the national government and the regional governments by the Constitution itself and both operate in their respective jurisdictions independently.
1. Dual Polity:-
The Constitution establishes a dual polity consisting of the Union at the Centre and the states at the Periphery. Each is endowed with sovereign powers to be exercised in the field assigned to them respectively by the Constitution. The Union government deals with the matters of national importance like defence, foreign affairs, currency and communication and so on. The state governments, on the other hand, look after the matters of regional and local importance like public order, agriculture, health, local government and so on.
2. Written Constitution:-
The Constitution is not only a written document but also the lengthiest Constitution of the world. Originally, it contained a Preamble, 395 Articles (divided into 22 Parts) and 8 Schedules. At present (2013), it consists of a Preamble, about 465 Articles (divided into 25 Parts) and 12 Schedules. It specifies the structure, organization, powers and functions of both the Central and state governments and prescribes the limits within which they must operate. Thus, it avoids the misunderstandings and disagreements between the two.
3. Division of Powers:-
The Constitution divided the powers between the Centre and the states in terms of the Union List, State List and Concurrent List in the Seventh Schedule. The Union List consists of 100 subjects (originally 97), the State List 61 subjects (originally 66) and the Concurrent List 52 subjects (originally 47). Both the Centre and the states can make laws on the subjects of the concurrent list, but in case of a conflict, the Central law prevails. The residuary subjects (ie, which are not mentioned in any of the three lists) are given to the Centre.
4. Supremacy of the Constitution:-
The Constitution is the supreme (or the highest) law of the land. The laws enacted by the Centre and the states must confirm to its provisions. Otherwise, they can be declared invalid by the Supreme Court or the High Court through their power of judicial review. Thus, the organs of the government (legislative, executive and judicial) at both the levels must operate within the jurisdiction prescribed by the Constitution.
5. Rigid Constitution:-
The division of powers established by the Constitution as well as the supremacy of the Constitution can be maintained only if the method of its amendment is rigid. Hence, the Constitution is rigid to the extent that those provisions which are concerned with the federal structure (i.e., Centre–state relations and judicial organisation) can be amended only by the joint action of the Central and state governments. Such provisions require for their amendment a special majority4 of the Parliament and also an approval of half of the state legislatures.
The Constitution establishes an independent judiciary headed by the Supreme Court for two purposes: one, to protect the supremacy of the Constitution by exercising the power of judicial review; and
two, to settle the disputes between the Centre and the states or between the states. The Constitution contains various measures like security of tenure to judges, fixed service conditions and so on to make the judiciary independent of the government.
The Constitution provides for a bicameral legislature consisting of an Upper House (Rajya Sabha) and a Lower House (Lok Sabha). The Rajya Sabha represents the states of Indian Federation, while the Lok Sabha represents the people of India as a whole. The Rajya Sabha (even though a less powerful chamber) is required to maintain the federal equilibrium by protecting the interests of the states against the undue interference of the Centre.