Yes, the Parliament and the State Legislatures have the power to make laws having retrospective operation (though it is generally avoided), except in those areas where there is a specific prohibition in the Constitution against retrospective operation of laws.
For example, clause (1) of Article 20 of the Constitution lays down as under:
“20. Protection in respect of conviction for offences.—(1) No person shall be convicted of any offence except for violation of a law in force at the time of the commission of the act charged as an offence, nor be subjected to a penalty greater than that which might have been inflicted under the law in force at the time of the commission of the offence.”
In view of this provision, the Parliament or a State legislature cannot make a law which defines a new offence retrospectively or which enhances punishment for an existing offence retrospectively.
Other than the above, there is no prohibition in the Constitution restricting making of a law having retrospective operation. However, as I mentioned above, usually a law having retrospective operation is not made even though it may be permissible. It is done only in rare cases where it is essential due to some peculiar reasons, such as to explain or remove some difficulties or some loopholes in law. This is to ensure undue hardship is not caused to people.
Dr. Ashok Dhamija is a New Delhi based Supreme Court Advocate and author of law books. Read more about him by clicking here. List of his Forum Replies. List of his other articles. List of his Quora Answers. List of his YouTube Videos.