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 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. 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.

Source: Laxmikant