JUDGMENT T. Vaiphei, J. 1. These six writ petitions involving a common question of law are heard together and are being disposed of by this common judgment. Ms. A Paul, the learned Counsel for the Petitioners in all the writ petitions, Mr AS Siddique, the learned Counsel for the State Respondents in WP(C) Nos. 255(SH) to 259(SH) of 2008 and Mr B Bhattacharjee, the learned Counsel appearing for the State Respondents in WP(C) No. 342(SH) of 2008 have been heard. It is the common ground of the learned Counsel appearing for the rival parties that these writ petitions are squarely covered by my decision dated 13.8.2010 in M/s Meghalaya Bitchem Private Limited vs. State of Meghalaya & Anr, in WP(C) No. 113(SH) of 2007. Nevertheless, for the sake of clarity, it will be more beneficial for all concerned to highlight the salient features of the instant writ petitions. All the writ Petitioners are aggrieved by the Notification bearing No. ERTS(T)64/98/314, dated 16-10-2006 issued by the State Government in the Taxation Department which is in the following terms : No. ERTS(T)64/98/314. In exercise of the powers conferred by Sub-section (5) of Section 8 of the Central Sales Tax Act, 1956, the Governor of Meghalaya is pleased to withdraw the benefit of exemption from payment of CST granted earlier under this Department's Notification No. ERTS(T)64/98/88, dated 12.04.2001 which was superseded by Notification No. ERTS(T)64/98/211, dated 5.9.2005, and to further direct in public interest that all industrial units eligible to 99% remission of VAT under para 3(2)(b) of the Meghalaya Industries (Tax Remission) Scheme, 2006 shall pay CST @ 1% provided the sale is made to a registered dealer outside the State or to the Government. Sales to others will attract normal rates of CST. Other industrial units which are eligible to 96% remission of VAT under the proviso to para 3(2)(b) of the Meghalaya Industries (Tax Remission) Scheme shall pay CST at normal rates as provided under Central Sales Tax Act, 1956. This Notification shall come into force with immediate effect. (BK Dev Verma) Principal Secretary to the Govt. of Meghalaya Excise, Registration, Taxation & Stamps Department 2. All the Petitioners are large and medium industries. According to them, the State-Respondents in the Meghalaya Industrial Policy, 1997 assured to provide them sales tax exemption for their finished goods for a period of seven years from the date of their commercial production. (BK Dev Verma) Principal Secretary to the Govt. of Meghalaya Excise, Registration, Taxation & Stamps Department 2. All the Petitioners are large and medium industries. According to them, the State-Respondents in the Meghalaya Industrial Policy, 1997 assured to provide them sales tax exemption for their finished goods for a period of seven years from the date of their commercial production. In furtherance of the Industrial Policy, the State Government had issued the Notification dated 12.4.2001 notifying the Meghalaya Industries (Sales Tax Exemption Scheme) 2001 declaring that the eligible units were entitled to Sales Tax exemption on sales of finished products manufactured by such eligible units within the State of Meghalaya and in the course of inter-State trade and commerce. In exercise of the powers conferred under Section 8(5) of the Central Sales Tax Act, 1956, the State Government issued another Notification on 12.4.2001 stating therein that no tax under the Central Sales Tax Act, 1956 shall be payable by an eligible industrial unit to whom an exemption certification in the form of Certificate of Authorization has been granted by the Commissioner of Taxes with the prior approval of the Taxation Department in respect of sale of goods manufactured by such units in the course of inter-State trade or Commerce during the period of validity of that certificate subject to the condition that such sale to any person outside the State of Meghalaya is supported by proper document of sale. This Notification came into force with effect from 12.8.1997. There is no dispute at the bar that all the Petitioners obtained the Eligibility Certificates under the Meghalaya Industrial Policy from the Managing Director, Meghalaya Industrial Development Corporation Limited (Respondent No. 4) certifying that they are eligible for claiming the incentives provided for in the Industrial Policy. Thus, the Petitioners have become eligible for the sales tax exemption. 3. The case of the Petitioners is that whereas the Notification dated 12.4.2001, the benefit of sales tax exemption was made available to all sales made in the course of inter-State commerce, the impugned Notification has restricted the benefit of sales tax exemption only to sales in the course of inter-State trade or commerce only to registered dealers or Government. 3. The case of the Petitioners is that whereas the Notification dated 12.4.2001, the benefit of sales tax exemption was made available to all sales made in the course of inter-State commerce, the impugned Notification has restricted the benefit of sales tax exemption only to sales in the course of inter-State trade or commerce only to registered dealers or Government. The further case of the Petitioners is that even after the enactment of Meghalaya Value Added Tax Act, 2003, in terms of Section 116 thereof, the sales tax exemption as promised in the Industrial Policy is continued in the form of Scheme of 2006. It is submitted by the Petitioners that the impugned Notification withdrawing the said sales tax exemption granted under the earlier Notification dated 12.4.2001, which had earlier been superseded by the Notification dated 5.9.2005 and directing that all industrial units eligible to 99% remission of VAT under para 3(2) of the Meghalaya Industries (Tax Remission) Scheme, 2006 shall pay CST @ 1% provided the sale is made to a registered dealer outside the State or to the Government while sales to others will attract normal rates of CST are contrary to the Meghalaya Industrial Policy, 1997 and the Meghalaya (Sales Tax Exemption) Scheme, 2001 formulated thereunder and are also hit by the doctrine promissory estoppel. According to the Petitioners, on the promise made by the State Respondents in the said Industrial Policy, each of them had taken steps for establishment of their industries by incurring huge amounts. Dealing with the same contentions, this is what I said in M/s Meghalaya Bitchem Private Ltd. (supra) at paragraph 13 and 14 of my judgment : 13... The question which falls for consideration in this writ petition is whether the impugned notification can be validly issued under the newly amended Section 8(5) of the Central Sales Tax Act, 1956. The effect of the legislative change introduced by the amending Act of 2002 is that on the coming into force thereof, the power of the States to grant exemption of sales tax for sale of goods in the course of inter-State trade or commerce is restricted to the sale by the dealer to a registered dealer. In other words, if such goods are not sold to a registered dealer, the States are deprived of their power to grant the tax exemption. In other words, if such goods are not sold to a registered dealer, the States are deprived of their power to grant the tax exemption. However, prior to the coming into force of 2002 amendment, no such restriction is placed upon the power of the States to grant the sales tax exemption irrespective of whether the sale of goods by the dealer in the course of inter-State trade or commerce was upon a registered dealer or not. A closer scrutiny of the Central Sales Tax Act, 1956 as amended in 2002 will reveal that the amendment came into force only with effect from 11.5.2002 and cannot, therefore, have retrospective effect. The Union Parliament and the State legislatures undoubtedly, have plenary powers of legislation within the fields assigned to them and subject to certain constitutional and judicially recognized restrictions can legislate prospectively as well as retrospectively. It is a cardinal principle of construction that every statue is prima facie prospective in operation unless it is expressly or by necessary implication made to have retrospective effect. This rule in general is applicable where the object of the statue is to affect vested rights or to impose new burdens or to impair existing obligations.-See GP Singh's principles of Statutory Interpretation Ninth Edn. at pp 437 38. There is nothing to indicate that the newly amended Section 8(5) of the Central Sales Tax Act, 1956 has any retrospective effect: the newly amended provision is evidently prospective in operation. Therefore, the contention of the State-Respondents that the notification dated 12.4.2001 is in conflict with newly amended Section 8(5) and that the impugned notification was issued on 5.9.2005 in conformity with the amended provision, does not hold water. In my judgment, the notification dated 12.4.2001 is not contrary to law when the same was issued. 14... Therefore, the contention of the State-Respondents that the notification dated 12.4.2001 is in conflict with newly amended Section 8(5) and that the impugned notification was issued on 5.9.2005 in conformity with the amended provision, does not hold water. In my judgment, the notification dated 12.4.2001 is not contrary to law when the same was issued. 14... The following principles for the application of the doctrine of promissory estoppel can be deduced from the above observations of the Apex Court : (a) a party must make an unequivocal promise, assurance or representation by word of conduct to the other party; (b) the representation was intended to create legal relations or affect the legal relationship, in future; (c) a clear foundation has to be laid in the writ petition, with supporting documents; (d) it has to be shown that the party invoking the doctrine has altered its position relying on the promise; (e) it is possible for the Government to resile from its promise when public interest would be prejudiced if the Government were required to carry out its promise (f) the doctrine cannot be pressed into service to compel the Government or public authority to carry out the representation or promise which is contrary to law or which was outside the authority or power of the officer of the Government or of the public authority to make; (g) the court will not apply the doctrine in the abstract. 15. As already found by me earlier, the Petitioner acting upon the unequivocal assurances made by the State Respondents under the Meghalaya Industrial Policy, 1997 set up a plant for production of Bitumen Emulsion and Allied Modified Bituminous Products by investing a project cost to the order of Rs. 268.71 lakhs. The representation was intended to create legal relationship between the Petitioner and the State-Respondents. The notification dated 12.4.2001 allowing tax exemption in respect of sales of goods in the course of inter-State trade or commerce not necessarily to a registered dealer did not fall foul of Section 8(5) of the Central Sales Tax Act, 1956 prior to its amendment, which came into force only with effect from 11.5.2002: the notification dated 12.4.2001 is, therefore, not contrary to law. No evidence is shown nor is such a plea made by the State-Respondents that public interest would be prejudiced if they are required to carry out the promise. No evidence is shown nor is such a plea made by the State-Respondents that public interest would be prejudiced if they are required to carry out the promise. Neither is it the case of the State-Respondents that the representation was made outside the authority or power of the officials to make. Under the circumstances, I have no alternative but to hold that the State-Respondents are barred by the doctrine of promissory estoppel from issuing the impugned notification which, ex facie, is bad in law. The Petitioner has, therefore, made out a clear case for the application of the doctrine of promissory estoppel to the facts of this case warranting the interference of this Court. 4. As the learned Counsel appearing for the State Respondents have conceded that the instant cases are covered by M/s Meghalaya Bitchem Private Limited (supra), the need for further discussion stands obviated. In the result, the Notification No. ERTS(T)64/98/314, dated 16.10.2006 issued by the Respondent No. 2 (Principal Secretary to the Government of Meghalaya, Department of Taxation) is not sustainable in law and is hereby quashed. Let a writ of mandamus issue restraining the State-Respondents from giving effect to the impugned notification. The parties are, however, directed to bear their respective costs.