Constitution of India, 1949
7. Rights of citizenship of certain migrants to Pakistan –
Notwithstanding anything in Articles 5 and 6, a person who has after the first day of March, 1947,migrated from the territory of India to the territory now included in Pakistan shall not be deemed to be a citizen of India:
Provided that nothing in this article shall apply to a person who, after having so migrated to the territory now included in Pakistan, has returned to the territory of India under a permit for resettlement or permanent return issued by or under the authority of any law and every such person shall for the purposes of clause (b) of Article 6 be deemed to have migrated to the territory of India after the nineteenth day of July, 1948.