All these four writ petitions are analogous in nature and are, therefore, taken up together for hearing as agreed to by the counsel for the parties and are exposed of by this common judgment. 2. In Civil Rule No.4162 of 1991, the petitioners mainly challenged the communication bearing No.Gau/ST/D-5/Circle 2/7253 dated 9th June, 1991 whereby the Superintendent of Taxes, Guwahati, Unit B, Kumarpara, intimated the petitioner/tea industries that its application for isssue of Authorisation Certificate under section 4 of the Assam Industries (Sales Tax Concessions) Act, 1986 could not be enterained in view of the provisions contained in Rule 2 (f) of the Assam Industries (Sales Tax Concession) Rules, 1988. The petitioners also questioned the vires of Rule 2 (f) of the aforesaid Rules, 1988 and sought for a writ of Mandamus commanding the respondents to exempt the petitioners from payment of sales tax for the period 14.4.88 to 13.4.93, and to direct the respondents to refund the sales tax amounting to Rs.8,74,985.89 which was paid till 31.7.91. 3. In Civil Rule No. 1474 of 1992, the petitioners mainly assailed the assessment orders by the Superintendent of Taxes, Nagaon for the periods ending 30.9.89, 31.3.90, 30.9.90, 31.3.91 and 31.3.92 in respect of M/s Milapchand Hiralal, Marwari Patty, Nagaon under the Assam Sales Tax Act, 1947 passed on 9.7.92. 4. In Civil Rule No.2172 of 1992, the petitioners assailed the order of assessment for the period ending 31.3.92, as passed on 5.8.92 by the Superintendent of Taxes, Nagaon under the Assam Sales Tax Act, 1947. 5. Similarly, in Civil Rule No.2345 of 1992, the petitioners assailed the assessment orders passed by the Superintendent of Taxes, Dhubri for the periods ending 31.3.89, 30.9.89, 31.3.90, 30.9.90, 31.3.91 and 31.3.92, in respect of M/s Netram Kanhaiyalal, Dhubri under the Assam Sales Tax Act, 1947. 6. In all the above civil rules M/s Dugar Tea Industries Pvt Ltd and Shri Bhanwarlal Dugar, are parties. The themetic content of all these writ petitions are based on exemption of sales tax under the Industrial Policy of Assam, 1986 announced by the State Govt for granting sales tax exemption to the specified units. 7. 6. In all the above civil rules M/s Dugar Tea Industries Pvt Ltd and Shri Bhanwarlal Dugar, are parties. The themetic content of all these writ petitions are based on exemption of sales tax under the Industrial Policy of Assam, 1986 announced by the State Govt for granting sales tax exemption to the specified units. 7. In Civil Rule No. 4162 of 1991, the petitioners claim that the petitioner industry was granted an Eligibility Certificate entitling the petitioner No.l to claim subsidy under the 1986 Incentive Scheme of the Govt of Assam for a period of three years and exemption from payment of sales tax with effect from 14.4.88 to 13.4.93, etc. After the enactment of the statute known as the Assam Industries (Sales Tax Concessions) Act, 1986 (Act 1 of 1987) hereinafter referred to as the Act, 1987, a set of Rules was framed which was known as the Assam Industries (Sales Tax Concessions) Rules, 1988, hereinafter referred to as the Rules, 1988. On the publication of the Rules, 1988, the petitioners contended that they applied to the respondent No. 7 for issuance of Authorisation Certificate by its letter dated 3.2.90, forwarding a copy of the same to the respondent No. 8. The respondent No. 8, by its communication dated 9.6.91 (Annexure M), expressed its inability to issue such Authorisation Certificate. In the writ petition, the petitioners also contended that while purchasing raw materials from the Guwahati Tea Auction Centre, the petitioners paid sales tax on purchase of tea to the extent of Rs.8,74,985.89, which according to the petitioners, was liable to be refunded by the respondents in view of the industrial policy. Petitioners, thus, questioned the action of the authorities refusing to give him Authorisation Certificate and also sought for exemption from payment of sales tax on the basis of the industrial policy by which, according to the petitioners, the respondents solemnly promised to grant sales tax exemption. In addition, petitioners also assailed the vires of Rule 2 (f) of the Rules, 1988. However, at the time of hearing, the learned counsel for the petitioner, did not seriously press on the question of vires. As alluded earlier, in all the remaining civil rules, the petitioners basically questioned the assessment orders basing its claim on the principle of Promissory Estoppel. 8. Mr. However, at the time of hearing, the learned counsel for the petitioner, did not seriously press on the question of vires. As alluded earlier, in all the remaining civil rules, the petitioners basically questioned the assessment orders basing its claim on the principle of Promissory Estoppel. 8. Mr. OP Bhati, learned counsel for the petitioner, fairly placed before me the statutory provisions of the Act of 1987 and the Rules 1988 apart from the assertions made in the writ petitions. The learned counsel also submitted that in view of the pronounced policy of the State for granting sales tax exemption, the petitioners acted on the representation of the authorities to their prejudice and the authorities now cannot rescind from the promises so far made. Mr. Bhati, the learned counsel, accordingly rested his plea on promissory estoppel. In support of his contention, the learned counsel for the petitioners referred to the decisions of the Supreme Court as reported in : (i) (1979) 2 SCC 409 , M/s Motilal Padampat Sugar Mills Co Ltd vs. State of UP & others; (ii) 1986 (Supp) SCC 728, Pournami Oil Mills & others vs. State of Kerela & another; (iii) 1987 (Suppl) SCC 710, State of Bihar & another vs. Usha Martin Industries Ltd; (iv) (1988) 3 SCC 570 , Assistant Commissioner of Commercial Taxes (Asstt) Dharwar & others vs. Dharmendra Trading Co & others; (v) (1992) 2 SCC 411 , Amrit Banaspati Co Ltd & another vs. State of Punjab & another; and (vi) (1992) 2 SCC 683 , M/s Pine Chemicals Ltd & others vs. Assessing Authority & others. 9. Mr. OP Bhati, the learned counsel for the petitioners, further contended that though appeal lies against the orders of assessment, since the orders of assessment were without jurisdiction, question of preferring appeals against those orders did not arise. In support of his contention, Mr. Bhati, the learned counsel, d referred to the decisions of the Supreme Court as reported in (i) AIR 1969 SC 556 , M/s Baburam Prakash Chandra Maheswari vs. Antarim Zila Parishad, Now Zila Parishad, Muzaffarnagar; (ii) AIR 1971 SC 33 ; L. Hriday Narain vs. Income Tax Officer, Bareilly; (iii) (1985) 3 SCC 267 , Ram and Shyam Co. vs. State of Haryana & others; and (iv) (1987) 4 SCC 525 , Dr. Kuntesh Gupta vs. Management of Hindu Kanya Mahavidyalaya, Sitapur (UP) & others. 10. vs. State of Haryana & others; and (iv) (1987) 4 SCC 525 , Dr. Kuntesh Gupta vs. Management of Hindu Kanya Mahavidyalaya, Sitapur (UP) & others. 10. The Act, 1987 was enacted to consolidate and amend the provisions of law relating to sales tax in the matter of concessions to industries. Section 3 of the Act, 1987 provides for sales tax concessions in respect of raw materials. Under section 3 (1): "...as from the commencement of this Act, no dealer shall be liable to pay any tax under such law in respect of the sale by him of any goods to a person possessing a valid authorisation certificate, hereinafter in this Act referred to as 'holder' if such goods are specified in such certificate as intended by the holder for use by him as raw materials in the manufacture of goods in the State for sale by him : Provided that..." 11. Sub-section (2) of section 3 of the Act, 1987 made it incumbent upon the dealer selling the goods, to furnish to the authority competent to assess him, a declaration duly filled and signed by the 'holder' as to whom the goods were sold containing the prescribed particulars in a prescribed form and obtained from the prescribed authority. Under sub-section (1) of section 4 of the Act, 1987, a person undertaking to manufature in the State such goods, as may be prescribed, may make an application in the prescribed, form to the prescribed authority and within the prescribed time for a Certificate of Authorisation for the purposes of sub-section (1) of section 3. If the authority to whom an application is made under sub-section (1) of section 4 is satisfied that the application is in conformity with the provisions of the Act and the rules made thereunder, it shall grant to the applicant a Certificate of Authorisation in the prescribed form which shall specify the class a or classes of goods for purposes of sub-section (1) of section 3 and the period for which it shall remain valid. Under sub-section (4) of section 4, no Certificate of Authorisation is to be granted under sub-section (2) except in respect of such raw materials as may be prescribed. Section 9 of the Act, 1987 provids for re-imburse-ment of sales tax paid on purchase of raw materials. Under sub-section (4) of section 4, no Certificate of Authorisation is to be granted under sub-section (2) except in respect of such raw materials as may be prescribed. Section 9 of the Act, 1987 provids for re-imburse-ment of sales tax paid on purchase of raw materials. By the said provision : 'The State Govt may, in the public interest and for promoting any prescribed industry or class of industry provide for reimbursement to any person in the manner and subject to such conditions as may be prescribed of the amount of tax paid under any sales tax law in respect of such goods as may be prescribed and used by such person as raw materials in the manufacture of goods in the State." 12. In the light of the Act, 1987, the existing sales tax laws were amended for providing sales/purchases tax concessions to raw materials and finished products. Provisions were accordingly made for exemption of sales/purchase tax to new industrial units. Section 3A which has been inserted after section 3, reads as follows: "3A. Notwithstanding anything contained in this Act the State Govt may, by notification in the Official Gazette and subject to such conditions as may be specified d therein, direct that no dealer shall be liable to pay tax under this Act in respect of sales of such goods produced by him in any such new industrial unit as may be 'specified in the notification for a period of five years from the date of commence­ment of production of such new industrial unit: Provided that exemption under this section shall not be granted in respect of any sale where the dealer has collected any amount by way of sales tax in any form or manner in respect of such sale. Explanation : For the purpose of this section, the clause 'new industrial unit' shall have the same meaning as in the Assam Industries (Sales Tax Concessions) Act, 1986..." 13. Similar provisions were made in the case of the Assam (Sales of Petroleum and Petroleum Products, including Motor Spirit and Lubricants) Taxation Act, 1955, the Assam Finance (Sales Tax) Act, 1956 as well as in the Assam Purchase Tax Act* 1967. Similar provisions were made in the case of the Assam (Sales of Petroleum and Petroleum Products, including Motor Spirit and Lubricants) Taxation Act, 1955, the Assam Finance (Sales Tax) Act, 1956 as well as in the Assam Purchase Tax Act* 1967. In exercise of the powers conferred under section 10 of the Act, 1987, the Govt of Assam made a set of Rules in the year 1988 which is known as the Assam Industries (Sales Tax Concessions) Rules, 1988. Rule 2 (f) of the Rules, 1988 defines'Raw material'which reads as follows : "2. (f) 'Raw material' means any material or commodity capable of being used for manufacture of any other product specified in any authorisation certificate as intended by the holder for use by him as raw material in the manufacture of goods in the State for sale by him but shall not include the following commodities, namely: (a) tea, (b) coal, (c) liquified petroleum gas, (d) plywood, (e) petrol, diesel oil and lubricants." 14. Rules 2 (f) of the Rules, 1988 cannot be held to be ultra vires on the ground of excessive delegation. By the Act, 1987 the Legislature laid down its legislative policy and the rule making authority while defining and prescribing the material and commodity capable of being used for manufacture of any other a product specified in the Authorisation Certificate as intended by the holder for use by him as raw materials, do not exceed the legislative policy and therefore, the rule cannot be said to be ultra vires. From the above provisions, it thus emerges that exemption from payment of sales tax is now regulated by the statute of 1987 and the rules framed thereunder, and the plea of estoppel cannot act as a spanner in the legitimate exercise of the statutory power. 15. The plea of estoppel should not also compel performance of any promise or undertaking which is contrary to the statute. The State, similarly, also cannot be interdicted from making its policy decisions; nor the legislative sovereignly in taking legislative measures can in any way be interfered by the principle of estoppel. Principle of estoppel should not estop public authorities from discharging its lawful duties and the authorities in exercising their statutory powers. The State, similarly, also cannot be interdicted from making its policy decisions; nor the legislative sovereignly in taking legislative measures can in any way be interfered by the principle of estoppel. Principle of estoppel should not estop public authorities from discharging its lawful duties and the authorities in exercising their statutory powers. In the case of M/s Motilal Padmapat Sugar Mills Co Ltd (supra), on which the petitioners have placed reliance, the Supreme Court observed that the doctrine of promissory estoppel cannot be applied in the teeth of obligation or liability imposed by law and there can be no promissory estoppel against the exercise of legislative powers. 16. I have already indicated that the real object of the petitioners was to get rid of the assessment orders passed by the statutory authority, but there was no proper pleading as such in any of these petitions. The pleadings only contained vague and bald expressions without being supported by any material. None of the petitions disclose as to the nature and extent of the act or actions undertaken by the petitioners on the basis of the promise made by the State/authorities. As indicated earlier, petitioners basically assailed the orders of assessment and only e collaterally raised the plea of promissory estoppel. However, considering the overall facts and circumstances of the case, I am of the view that no injustice as such is caused to the petitioners by the impugned actions of the respondents/ authorities and accordingly, all the four writ petitions are dismissed with a cost of Rs.5,000/- in each case.