Article 303 of Constitution of India "Restrictions on the legislative powers of the Union and of the States with regard to trade and commerce"
(1) Notwithstanding anything in Article 302, neither Parliament nor the Legislature of a State shall have power to make any law giving, or authorising the giving of, any preference to one State over another, or making, or authorising the making of, any discrimination between one State and another, by virtue of any entry relating to trade and commerce in any of the Lists in the Seventh Schedule.
(2) Nothing in clause (1) shall prevent Parliament from making any law giving, or authorising the giving of, any preference or making, or authorising the making of, any discrimination if it is declared by such law that it is necessary to do so for the purpose of dealing with a situation arising from scarcity of goods in any part of the territory of India.
Article 304 of Constitution of India "Restrictions
on trade, commerce and intercourse among States"
Notwithstanding anything in Article 301 or Article 303, the
Legislature of a State may by law -
(a) impose on goods imported from other States or the Union
territories any tax to which similar goods manufactured or
produced in that State are subject, so, however, as not to
discriminate between goods so imported and goods so
manufactured or produced; and
(b) impose such reasonable restrictions on the freedom of
trade, commerce or intercourse with or within that State as
may be required in the public interest:
Provided that no Bill or amendment for the purposes of
clause shall be introduced or moved in the Legislature of a
State without the previous sanction of the President.