S.K.DAS, J.

(1) THIS is a writ petition under Art. 32 of the Constitution. The petitioners, Messrs. Nand Lal Raj Kishan, carry on a business of commission agents at Delhi and are liable to pay sales tax in respect of their business under the provisions of the Bengal Finance (Sales Tax) Act, 1941, as in force in Delhi. They filed returns for four quarters of 1954-55 and claimed exemption in respect of sales of certain goods to the registered dealers under the provisions of s. 5(2)(a)(ii) of the said Act. By his order dated April 11, 1956, the Sales Tax Officer disallowed the exemption claimed by the petitioners mainly on the ground that the alleged sales were made to "those registered dealers whose activities had gone under-ground." The Sales Tax Officer issued a demand notice for a sum of Rs. 1,11,890-11-0 on account of sales tax. The petitioners then carried an appeal to the Assistant Commissioner of Sales Tax, Delhi. The Assistant Commissioner set aside the order of the Sales Tax Officer and remanded the case for a fresh decision in the light of certain judgments given by the Chief Commissioner, Delhi, in a number of similar cases. In the meantime, the Bengal Finance (Sales Tax) Act, 1941, was amended by the Bengal Finance (Sales Tax) (Delhi Amendment) Act, 1956, being Act No. 17 of 1956. This amending Act which came into force on October 27, 1956, inserted a new section, which is s. 8A of the Act. This section reads as follows:

"S. 8A. Security from certain class of dealers. The Commissioner, if it appears to him to be necessary so to do for the proper realisation of the tax levied under this Act, may impose for reasons to be recorded in writing as a condition of the issue of a registration certificate to a dealer or of the continuance, in effect, of such a certificate issued to any dealer, a requirement that the dealer shall give security up to an amount and in the manner approved by the Commissioner for the payment of the tax for which he may be or become liable under this Act."

(2) ON May 17, 1957, the petitioners asked for a fresh registration certificate on the ground that their original certificate had been lost in transit. They further asked for the addition of some more items of goods in the registration certificate, .such as cigarettes, bidis and glass of all kinds. Thereupon the Sales Tax Officer made certain enquiries and found that the petitioners had been frequently shifting their places of business and the sales alleged to have bean made by them to gome registered dealers were not genuine, because those persons could not be traced at the addresses given. On a report being submitted to the Commissioner of Sales Tax, Delhi, the Commissioner asked the Sales Tax Officer to issue a notice to the petitioners. On July 13,1957, such a notice was issued to the petitioners to show cause why they should not be asked to furnish a security of Rs. 10,000 in accordance with the provisions of s. 8A. The petitioners then appeared before the Sales Tax Officer and made a statement that they were not prepared to deposit any amount as security. They also filed a written explanation objecting to the demand of security. The matter was then referred to the Commissioner of Sales Tax who considered the explanation of the petitioners and the report of the Sales Tax Officer. The Commissioner expressed his finding in the following words:

"IN view of the reputation that the dealer enjoys in the market, namely, that he being a commission agent has been engaged in the business of selling goods to other commission agents, all sales being effected to unscrupulous registered dealers, frequent changes in the name and place of business without giving specific details, late submission of information regarding the changes in the name and place of business, non-submission of returns for the year 1956-57 within the prescribed time, it appears necessary to demand security under section 8A of the Bengal Finance (Sal