( 1. ) THE petitioner, a partnership firm, carries on business in automobiles, spare parts and other goods at Indore and is a registered dealer under the M. P. General Sales Tax Act, 1958 (hereinafter called the Act ). For the period 1st April, 1967, to 31st March, 1968, the petitioner-firm filed four quarterly returns; but all these returns were admittedly filed late. The petitioner was accordingly given a notice (annexure A) dated 25th September, 1970, requiring the petitioner, inter alia, to show cause why penalty under Sub-section (3) of Section 17 of the Act should not be imposed on the petitioner. The petitioner then filed a reply (annexure B) showing cause against imposition of penalty, in which it was stated, relying on the decision of this Court in Pyarelal v. State of M. P. 1971 M. P. L. J. 249, that mere late filing of return did not render the dealer liable for penalty under Section 17 (3) of the Act. The assessment order in the present case was passed on 31st March, 1971, in which there was no decision relating to imposition of penalty.

( 2. ) IN the meantime, on 6th May, 1971, the M. P. General Sales Tax (Amendment and Validation) Act, 1971 (No. 13 of 1971), hereinafter called the amending Act, came into force by which Section 17 of the principal Act was amended by addition of Sub-section (1-A) and substitution of a new Sub-section (3) therein. This amending Act was given retrospective effect and it was expressly stated that Section 17, amended in this manner, was to be deemed to have formed part of the principal Act from the commencement thereof. Obviously, the amendment of Section 17 by the amending Act in this manner was made to counteract the decision of this Court in the Pyarelals case 1971 M. P. L. J. 249. There is no dispute that by virtue of the amended Section 17 a dealer is liable for imposition of penalty for mere late filing of the return. For this reason, there is no dispute that in case retrospective effect can be given to the amendment made in Section 17, in the manner provided in the amending Act, so as to treat the amended Section 17 as forming part of the principal Act from the commencement thereof, the petitioner would clearly be liable to imposition of penalty.

( 3. ) ACTING on the basis of the aforesaid amendment in Section 17 of the principal Act, the Assistant Commissioner of Sales Tax (respondent No. 1) passed an order (annexure C) dated 29th July, 1971, imposing a total penalty of Rs. 56,225 under Section 17 (3) of the Act on the petitioner.

( 4. ) BY this petition under Article 226 of the Constitution the petitioner challenges the imposition of penalty on it by the impugned order (annexure C) dated 29th July, 1971, and seeks a writ to quash the same.

( 5. ) THE only contention of Shri G. M. Chaphekar, the learned counsel for the petitioner, is that the amendment made in the above manner in Section 17 of the principal Act by the Amending Act No. 13 of 1971 is ultra vires Article 20 of the Constitution. The argument is that this retrospective amendment in the principal Act violates Article 20 (1) of the Constitution by providing a penalty for an act which did not attract penalty when it was done. The question before us is whether this contention alone advanced in support of this petition is tenable.

( 6. ) ARTICLE 20 (1) of the Constitution with which alone we are concerned reads as under : 20. (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. A plain reading of the above constitutional provision indicates that it contains a prohibition only against retrospective criminal law since the word "offence" used therein is significant. The word "penalty" also used later in Clause (1) of Article 20 has to be read along with the word "offence" occu