I.A. Ansari, J.

1. Can a subordinate legislation be retrospective in operation, when the parent legislation, where under such a legislation stands made, is prospective in nature? When a person is statutorily entitled to be exempted from payment of sales tax, or is statutorily entitled to pay tax at a reduced rate, can such benefit of exemption, or payment of tax at a reduced rate, be denied to him on equitable consideration, because of the fact that the person had already availed exemption from payment of sales tax, or had availed of the benefit of payment of sales tax at a reduced rate during the period, when he was not so entitled to avail such benefit? In short, whether, on equitable considerations, a person can be denied the benefit of exemption from payment of sales tax, or the benefit of payment of sales tax at a reduced rate, which the legislature has, otherwise, vested in him?

2. In the answers to the questions, posed above, rest the decision in this appeal. However, an incidental question, which we have to answer, in this appeal, has also arisen, and the question is: when a statutory authority, while determining the question of reopening of assessment of taxable liability, acts on the basis of the clarification, which such an authority obtains from his superior authority, on the issue raised in the proceedings of reopening of assessment, and opens the assessment and makes assessment on the basis of the clarifications received from his superior authority, whether such an action is sustainable in law, particularly, when, there is no independent application of mind by the authority, who re-opens the assessment as to whether the clarification, as given by his superior authority, are attracted to the facts of the case or not?

3. The questions, indicated above, have arisen in the context of Section 9 of the Assam General Sales Tax Act, 1993 (in short, 'the AGST Act, 1993'), which, in some specified cases, provides for granting of exemption from payment of tax in respect of sale of goods and empowers the State Government to issue notification granting exemption from payment of sales tax, or payment of sales tax at a reduced rate inasmuch as the root of the controversy lies in the notification, dated 03.01.2003, published in the Assam Gazette (Extraordinary) on 22.01.2003, whereby the rates of payment of tax, on the sale/supply of certain classes of goods including water supply and sanitary fittings, pipes used for the purpose, specified in the notification, were reduced if the goods were sold by a dealer, registered under the AGST Act, 1993, to the Government of India, Government of Assam and to any undertaking, corporation or enterprises of the Government of India or of the Government of Assam, for the purpose of their own use provided that a certificate, in writing, as prescribed by Form 'C', was issued, in this regard, in favour of the dealer ?

4. Before attempting to answer the questions, raised above, the legal history behind the notification, dated 03.01.2003, aforementioned needs to be traced. In this regard, it is pertinent to note that though the sale of PVC pipes were taxable @ 13.2% under the AGST Act, 1993, the State Government could not have realized more than 4.4% of tax on the turnover from a dealer, who sold PVC pipes, at any place, outside the territory of the State of Assam, for being carried to, and used in, the State of Assam, because such transactions amounted to inter-State sale; whereas a local manufacturer, in Assam, was required to pay tax @ 13.2%, because the sale of PVC pipes by a local manufacturer, within the State of Assam, even if such sale was made to the Government of India, Government of Assam and or to any undertaking, corporation, enterprise of the Government of India or of the Government of Assam for the purpose of use by the Government undertakings, corporations or enterprises aforementioned amounted to intra-State sale and nor inter-State sale.

5. In other words, while the manufactur