The president can declare a national emergency under article 352, when the security of India or a part of it is threatened by war or external aggression or armed rebellion. The normal fabric of the Centre-state relations undergoes a basic change during national emergency.

Effect on Centre-state relations

1. Executive
   
   

In normal times, the Centre state can give executive directions to a state only on certain specified matters. However, during a national emergency, Centre becomes entitled to give executive directions on any matter. Thus, the state governments are brought under the complete control of the Centre, though they are not suspended.

The Parliament becomes empowered to make laws on any subject mentioned in the state list. Although the legislative power of state legislature is not suspended, it becomes subject to the overriding power of the Parliament. President can issue ordinances on the state subject, if the Parliament is not in session.

 In brief the Constitution becomes unitary than federal.

The president can modify – reduce or cancel, the constitutional distribution of revenues between the Centre and the states. Such modification continues till the end of the financial year in which the emergency is revoked.

 National emergency was proclaimed thrice. During this time the Centre becomes all powerful. The constitutions become unitary rather than federal without even amending the Constitution. However these powers are a necessary evil to enable central government to meet any abnormal situations effectively.