Article 355 of Constitution of India "Duty of the Union to protect States against external aggression and internal disturbance"
It shall be the duty of the Union to protect every State against external aggression and internal disturbance and to ensure that the government of every State is carried on in accordance with the provisions of this Constitution.
Article 356 of Constitution of India "Provisions in case of failure of constitutional machinery in State"
(I) If the President, on receipt of report from the Governor of the State or otherwise, is satisfied that a situation has arisen in which the government of the State cannot be carried on in accordance with ?he provisions of this Constitution, the President may be Proclamation-
(a) assume to himself all or any of the functions of the
Government of the State and all or any of the powers vested
in or exercisable by the Governor or any body or authority
in the State other than the Legislature of the State;
(b) declare that the powers of the Legislature of the State
shall be exercisable by or under the authority of
Parliament;
(3) make such incidental and consequential provisions as
appear to the president to be necessary or desirable for
giving effect to the objects of the Proclamation, including
provisions for suspending in whole or in part the operation
of any provisions of this constitution relating to any body
or authority in the State.
Provided that nothing in this clause shall authorise the
President to assume to himself any of the powers vested in
or exercisable by a High Court, or to suspend in whole or in
part the operation of any provision of this Constitution
relating to High Courts.
(2) Any such Proclamation may be revoked or varied by a
subsequent Proclamation.
(3) Every Proclamation issued under this Article except
where it is a Proclamation revoking a previous Proclamation,
cease to operate at the expiration of two months unless
before the expiration of that period it has been approved by
resolutions of both Houses of Parliament. Provided that if
any such Proclamation (not being a Proclamation revoking a
previous Proclamation) is issued at a time when the House of
the People is dissolved or the dissolution of the House of
the People takes place during the period of two months
referred to in this clause, and if a resolution approving
the Proclamation has been passed by the Council of States,
but no resolution with respect to such Proclamation has been
passed by the House of the People before the expiration of
that period, the Proclamation Shall cease to operate at the
expiration of thirty days from the date on which the House
of the People first sits after its reconstitution unless
before the expiration of the said period of thirty days a
resolution approving the Proclamation has been also passed
by the House of the People.
(4) A Proclamation so approved shall, unless revoked, cease
to operate on the expiration of a period of six months from
the date of issue of the Proclamation: Provided that if and
so often as a resolution approving the continuance in force
of such a Proclamation is passed by both Houses of
Parliament, the Proclamation shall, unless revoked, continue
in force for a further period of six months from the date on
which under this clause it would otherwise have ceased to
operating, but no such Proclamation shall in any case remain
in force for more than three years:
Provided further that if the dissolution of the House of the
People takes place during any such period of six months and
a resolution approving the continuance in force of such
Proclamation has been passed by the Council of States, but
no resolution with respect to the continuance in force of
such Proclamation has been passed by the House of the People
during the said period, the Proclamation shall cease to
operate at the expiration of thirty days from the date on
which the House of the People first sits after its
reconstitution unless before the expiration of the said
period of thirty days a resolution approving the continuance
in force of the Proclamation has been also passed by the
House of the People.
(5) Notwithstanding anything contained in clause (4), a
resolution with respect to the continuance in force of a
Proclamation approved under clause (3) for any period beyond
the expiration of one year from the date of issue of such
proclamation shall not be passed by either House of
Parliament unless-
(a) a Proclamation of Emergency is in operation, in the
whole of India or, as the case may be, in the whole or any
part of the State, at the time of the passing of such
resolution, and
(b) the Election Commission certifies that the continuance
in force of the Proclamation approved under clause (3)
during the period specified in such resolution is necessary
on account of difficulties in holding general elections to
the Legislative Assembly of the State concerned:
Provided that in the case of the Proclamation issued under
clause (1) on the 6th day of October, 1985 with respect to
the State of Punjab, the reference in this clause to "any
period beyond the expiration of two years".