One of the most important aspects of Indian Constitution is the Federal nature of the Constitution. Constitutions are divided between federal and unitary. United States is a classical example of a Federal Constitution.
In a unitary Constitution, all powers are vested in the Central Government to which the authorities in the units are subordinate and function as\the agents of the Government at the Centre and exercise authority by delegation from the Centre.
In case of a federal polity, under normal circumstances the Constitution is rigid, written and powers are divided between the Federal Government and that of the Provincial Governments.
In case of Indian Constitution, it has been variously described as quasi-federal, federal with a strong unitary, federal in structure but unitary in spirit, federal in normal times but with possibilities of being converted into a purely unitary one during the Emergency. It is extremely difficult to put our Constitution in any strict mould of a federal or unitary type. It cannot be considered as Unitary because
1. It provides for distribution of executive and legislative powers between the Union and the States and
2. Provisions affecting the powers of the States or Union-State the centre cannot amend relations without ratification by the States.
It cannot be considered strictly federal because the residuary powers vest in the Union. As Dr.Ambedkar’s rightly pointed out, rigidity and legalism were the two serious weaknesses of federalism, the Indian constitutions is unique in that it created a dual polity with a single Indian citizenship which could be both unitary and federal according to requirements of time and circumstances.
Here are some of the important articles in our Constitution, which are Unitary in character.
1. Under Article 249, the Union Parliament can invade the State List.
2. Under Articles 356 and 357, on the ground of failure of constitutional machinery in the State, all its executive and legislative powers may be taken over by the Union.
3. Under Articles 352 to 354, the Constitution can be converted into an entirely unitary one inasmuch as during the Proclamation of Emergency, the executive and legislative powers of the Union extend to matters even in the State List.
4. Under Articles 2,3 and 4, new States may be formed and areas, boundaries or names of existing States altered by the Union Parliament by the Union Parliament by ordinary law passed by simple majority votes.