The Constitution of India
§304 — 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 (b) shall be introduced or moved in the Legislature of a State without the previous sanction of the President.