Under Article 355 of the Constitution of India, it is the duty of the Union to :
1
Protect States against external aggression and internal disturbance
2
Allow the extension of executive powers of the Union of any state
3
Declare that the powers of the legislature of a State shall be exercisable by or under the authority of the parliament
4
Allow the parliament to include or exclude any caste, race or tribe into the list of the Scheduled Castes or Scheduled Tribes