As many as nine industrial units viz Manjushree Extrusions Ltd, A. Bakers Pvt Ltd, GW Mills Ltd, United Soft Drinks Pvt Ltd, Sunrise Biscuit Co Ltd, MCIP Ltd, AA Steel Ltd and M/s KU Pvt Ltd, filed as many as nine writ petitions before the learned Single Judge in which the basic relief claimed by them was that they were entitled to full sales tax exemption as was contemplated by the Industrial Policy of 1991 issued by the State of Assam if they undertake expansion, modernisation and diversification work in their existing industrial units to the extent of at least 25% in capital investment and 10% in additional employment. It was further the case of the industrial units in the writ applications that having granted full sales tax exemption, the Govt of Assam could not issue notification in the year 1995 and frame a scheme contrary to the one which was framed in the year 1991. According to the industrial units, a right, which was vested in the industries, viz, the right to claim full sales tax exemption, has been illegally taken away by issuance of a notification in the year 1995 and this is what could not precisely be done in law. The learned Single Judge dismissed the writ petitions of all the industrial units by holding to the industrial units undertaking expansion, modernisation and diversification to the extent of 25%, were not entitled to the grant of full sales tax exemption The industrial units filed writ appeals before a Division Bench of this Court which came up for hearing before the Smti Meera Sharma, J. and Shri D. Biswas, J. The leading judgment was written by Smti Meera Sharma, J. holding that the appellants were entitled to full sales tax exemption under the Policy of 1991 and that the same could not be taken away by the Policy of 1995. It has also been found by Smti Meera Sharma, J. that once the State had promised full sales tax exemption, it could not divest the industrial units of that full sales tax exemption by inserting different words in the policy of 1995. It has also been found by Smti Meera Sharma, J. that once the State had promised full sales tax exemption, it could not divest the industrial units of that full sales tax exemption by inserting different words in the policy of 1995. Shri D. Biswas, J. while not disagreeing with Smti Meera Sharma, J. that if a benefit has been conferred, the same could not be taken away by the State, has disagreed to the extent that both the policies of 1991 and 1995 were similar in nature and that the appellants were not entitled to full sales tax exemption (1993 (3) GLJ 468). Since there was difference of opinion between the two Judges, the matters stood referred for opinion of the third Judge. Hon'ble the Chief Justice Shri Brijesh Kumar (as he then was) ordered placement of the matters before me for opinion. This is how the cases have come up for hearing before me for my opinion as to which view is correct. 2. It is agreed between the counsel for the parties that since a common question has arisen in all these cases, all the eases can be and should be disposed of together. In view thereof, I, by virtue of this judgment, would be disposing of all these matters (Writ Appeals Nos 139 of 1998, 140 of 1998, 141 of 1998,153 of 1998, 154 of 1998, 155 of 1998, 156 of 1998, 163 of 1998 and 164 of 1998) together. In order to appreciate the precise controversy between the parties, it would be necessary to have a look at the very wordings of the Industrial Policy of 1991 (herein after called Policy of 1991) and the notification of the Assam Govt issued in the year 1995 (herein after called the notification of 1995). The relevant provisions of the Policy of 1991, are reproduced below : "2. The relevant provisions of the Policy of 1991, are reproduced below : "2. Eligible Unit: Only new units set up on or after 1.4.1991 and existing units undertaking expansion, modernisation or diversification at the same location or at any other place in the State of Assam will be eligible for incentives under 1991 Scheme provided that: 2.1 A unit shall have employment of 80% people of Assam in the managerial cadre and 90% people of Assam in the non-managerial cadre and that over a period of 5 years from the commencement of production such units would take all effective steps to ensure 100% employment of people of Assam in non-managerial and atleast 90% in managerial posts. They would further give an undertaking that if these conditions are violated, the State Government Subsidies/Incentives so availed by them would be fully refunded. 3. New Unit: An industrial unit which has taken all the initial effective steps on or after 1.4.91 would be considered as a new unit. 4. Existing Unit: A unit which is or was in commercial production at any time prior to 1.4.91 will be considered as an existing unit for the purpose of the 1991 Scheme. 5. Expansion/Modernisation/Diversification : Expansion/modernisation/ diversification of an existing industrial unit will be eligible for all incentives if the total capital investment on plant and machinery in the expansion/modernisation or diversification as the case may be, is more than 25 percent of the total fixed capital investment of the existing unit. For the purpose of calculation, gross value of all the capital investments made on land, building, plant & machinery of an existing unit will be taken into consideration. Expansion/modemisation/diversification will imply an increase of at least 25% in the existing installed capacity as well as increase of additional employment at least by 10%. The fact that existing unit have availed itself of incentives will not disqualify the expansion/modernisation/diversification project to get incentives for the extra investment made. 6. Sales Tax Exemption : Sales tax will be exempted on purchase of raw materials and sales of finished products for a period of seven years." 3. Having reproduced the relevant provisions of the Policy of 1991, it would be appropriate to reproduce the relevant provisions of notification of 1995. The same read as under : "7. 6. Sales Tax Exemption : Sales tax will be exempted on purchase of raw materials and sales of finished products for a period of seven years." 3. Having reproduced the relevant provisions of the Policy of 1991, it would be appropriate to reproduce the relevant provisions of notification of 1995. The same read as under : "7. Determination of increase in production of an industrial unit which undertakes expansion/modernisation/diversification : The actual production of the industrial unit during 365 consecutive working days of the unit, preceding the date of completion of its expansion/modernisation/diversification shall be called its base year production. The actual production of the industrial unit after its expansion/modernisation/ diversification, shall be determined on an yearly basis, the first year being the 365 working days, following the date of commencement of production after the completion of the expansion/modernisation/diversification. Increase in production of an industrial unit after the completion of expansion/modernisation/diversification shall be equal to the annual production after the completion of expansion/ modernisation/diversification minus production during the base year divided by the base year production, expressed in percentage. 10. Procedure for the extension of the benefit under this scheme to an eligible industrial unit of the Category B, which obtains the certificate of authorisation on or after the date of issue of this notification, dated the 16th August, 1995 with effect from the date of issue of this notification or thereafter : (a) With regard to the purchase of permitted raw materials, as stated in the certificate of authorisation, granted to an industrial eligible unit, of the Category B under this para 10, the following shall be the procedure: Under this scheme, an eligible existing industrial unit, undertaking expansion/ modernisation/diversification, fulfilling all conditions and norms and holding the certificate of authorisation shall be entitled to the benefit of full sales tax relief in the purchase of permitted raw materials, stated in the certificate of authorisation, granted to it by the Assessing Officer of the area to such extent as are required for achieving the difference between actual annual production after the completion of the expansion/ modernisation/diversification and the annual production during the base year. The relief as aforesaid shall be allowed by way of refund to such eligible industrial unit on application, filed before the Assessing Officer of the area within 90 days from the date of expiry of the financial year to which the refund relates. The relief as aforesaid shall be allowed by way of refund to such eligible industrial unit on application, filed before the Assessing Officer of the area within 90 days from the date of expiry of the financial year to which the refund relates. The refund shall be governed by the provision of section 30 of the Assam General Sales Tax Act, 1993 and the Rules made thereunder. Provided that.... (b) With regard to the sales of the finished products, the following shall be the procedure: Corresponding to the difference between the actual annual production after the completion of expansion/modernisation/diversification and the annual production during the base year, the holder of the certificate of authorisation in the case of an eligible industrial unit of the Category B shall be competent to sell his finished products in the State of Assam or in the course of inter State trade or commerce, for which he shall not be liable to pay sales tax under the Assam General Sales Tax Act, 1993. In the cash memorandum or the bill, issued to the purchaser, the holder of the certificate of authorisation shall clearly mention the reference particulars of his certificate of authorisation and such copy of the cash memorandum or bill shall be verified by the Assessing Officer of the area at the time of assessment of his Sales Tax dues. Provided that.... 11. Procedure for the extension of benefit under the scheme to an eligible industrial unit under the Category B, which obtains the certificate of authorisation on or after the date of issue of this notification, dated the 16th August, 1995, but whose certificate of authorisation is in force prior to the date of issue of this notification dated the 16th August, 1995, but from or after 1.4.91 : (a) (i) Corresponding to the extent of requirements of the permitted raw materials (stated in the certificate of authorisation, granted to the aforesaid industrial unit) in reference to the difference between the actual annual production after the completion of the expansion/modernisation/diversification and the annual production during the base year, the benefit of sales tax, as entitled under the scheme shall be allowed by way of refund to such eligible industrial unit on application, filed before the Assessing Officer of the area within 180 days from the date of issue of the certificate of authorisation. The refund shall be governed by the provision section 30 of the Assam General Sales Tax Act, 1993 and rules made thereunder. (ii) During the period from or after the date of this notification dated the 16th August, 1995, the benefit of sales tax relief as entitled under this scheme in the purchase of permitted raw materials stated in the certificate of authorisation granted to any of the above mentioned eligible industrial units of Category B under this para 11 shall be available to it in the same manner as laid down in sub-para (a) of para 1.0. Provided.... (b) With regard to the sale of the finished products, the following shall be the procedure: Corresponding to the difference between the actual annual production after the completion of expansion/modernisation/diversification and the annual production during the base year, the holder of the certificate of authorisation in the case of an eligible unit of the Category B under this para 11 shall be competent to sell his finished products in the State of Assam or in the course of inter-State trade or commerce, for which he shall not be liable to pay sales tax under the Assam General Sals Tax Act, 1993. In the cash memorandum or the bill, issued to the purchaser, the holder of the certificate of authorisation shall clearly mention the reference particulars of his certificate of authorisation and such copy of the cash memorandum or bill shall be verified by the Assessing Officer of the area at the time of assessment of his sales tax dues..... .... ...." 4. While interpreting the 1991 Policy and 1995 Scheme, Smti Meera Sharma, J, held that the Industrial Policy of 1991 provided sales tax exemption to new industrial units as well as existing industrial units undertaking expansion/ modernisation/diversification for a period of seven years. It has been held that the Scheme of 1995 limiting sales tax exemption only on increased production was improper and that the incentives granted under Industrial Policy of 1991 could not be curtailed by the Scheme of 1995. It is further the finding of Smti Meera Sharma, J. that the Scheme of 1995 was in continuation of 1991 Industrial Policy and that Eligibility Certificate issued by the implementing agency created enforceable rights and that the Court could issue writ of Mandamus for implementing the policy decision. It is further the finding of Smti Meera Sharma, J. that the Scheme of 1995 was in continuation of 1991 Industrial Policy and that Eligibility Certificate issued by the implementing agency created enforceable rights and that the Court could issue writ of Mandamus for implementing the policy decision. The relevant observations made by Smti Meera Sharma, J. are reproduced below for ready reference : "41. The Supreme Court in Bakul Oil Industries vs. State of Gujarat, (1987) 1 SCC 31 , held thus: "We must, however, observe that the power of revocation of withdrawal would be subject to one limitation, viz, the power cannot be exercised in violation of the rule of promissory estoppel. In other words, the Govt can withdraw an exemption granted by it earlier if such withdrawal could be done without offending the rule of promissory estoppel and depriving an industry entitled to claim exemption from payment of tax under the said rule. If the Govt grants exemption to a new industry and if on the basis of the representation made by the Govt an industry is established in order to avail the benefit of exemption it may then follow that the new industry can legitimately raise a grievance that the exemption could not be withdrawn except by means of legislation having regard to the fact that promissory estoppel cannot be claimed against a statute. The aforesaid law was again reiterated by the Supreme Court in Pine Chemicals Ltd. vs. Assessing Officer, (1992) 2 SCC 683 . 42. The learned counsel for the respondents in their argument did not dispute the validity of the contentions of the appellants that the incentives granted under the Industrial Policy cannot be curtailed/denied by framing a scheme, in the instant case the Scheme 1995. The ratio enunciated in the judicial pronouncement mentioned above is that principle of promissory estoppel and legitimate expectation require regularity, predictability and certainty in the Govt's dealing with the public. These principles may not be source of Constitutional Code, but are the consequence of rights of individual/public on substantive effect of Govt action as defined and enforced by the Courts. As submitted by Dr. Saraf, promissory estoppel has arisen with legitimate expectation on the decision of the respondent State Govt from the incentives already given by the 1991 Industrial Policy and that by the subsequent Scheme 1995 the same benefit be given to them. As submitted by Dr. Saraf, promissory estoppel has arisen with legitimate expectation on the decision of the respondent State Govt from the incentives already given by the 1991 Industrial Policy and that by the subsequent Scheme 1995 the same benefit be given to them. It is an admitted fact that the industrial units of the appellants were in production prior to 1.4.91 and they undertook expansion, modernisation and diversification of their existing industries and have received the benefits with promise till end of seven years. Hence, in our view, when the appellants are in receipt of the benefits as per the Scheme 1991 it cannot be curtailed by another Scheme. 43. For the foregoing reasons, we hold that the Scheme 1995 is the continuation of the 1991 Industrial Policy, hence appellants are entitled to the benefits of Scheme 1995. The Govt can give exemption from payment of tax under the scheme. It is for the policy makers, i.e. the Govt to decide whether as per the Scheme 1995, sales tax concession can be given to these appellants in the light of the benefits givenunder the Scheme, 1991, which have been enjoying by them for seven years. This Court can issue a writ of Mandamus to the Govt for implementation of the policy decision for the reasons discussed above. 44. Further, we have examined the contents of the Eligibility Certificate issued by die Implementing Agency to the appellants. These certificates created enforceable rights to the appellants and the writ Court as an appellate Court cannot review the same when these certificates were issued on the basis of a particular Scheme as a policy matter. 45. As discussed above, the Scheme 1995 is the continuation of Scheme 1991 so far it relates to Clause (5) of 1991 Policy. Therefore the Scheme 1995 is applicable subject to the scrutiny and enquiry made by the Govt. The appellants are at liberty to approach the respondents/Govt for implementation of the Scheme 1995 and for the benefits in the light of the Scheme 1991. The Govt may pass appropriate orders within a period of six weeks from the date of receipt of such representation from the appellants." 5. Mr. The appellants are at liberty to approach the respondents/Govt for implementation of the Scheme 1995 and for the benefits in the light of the Scheme 1991. The Govt may pass appropriate orders within a period of six weeks from the date of receipt of such representation from the appellants." 5. Mr. D. Biswas, J, while not disagreeing with the view of Smti Meera Sharma, J. to the extent that the promise made in 1991 could not be resiled by the State, has held that the incentives promised by the Industrial Policy of 1991 were neither taken away nor restricted by 1995 Scheme and that there was no difference in promise made m Industrial Policy of 1991 and the Scheme of 1995. According to the learned Judge, Industrial Policy of 1991 extended full sales tax exemption for seven years to new units while restricted the benefits to existing units to the extent of expanded industrial activity only. It would be fruitful to reproduce the exact observations of D. Biswas, J : "56. It would appear from para B that the appellants who are in production prior to 1.4.91 fall within the above category and they have been given limited benefit only for the expansion/modernisation or diversification subject to certain conditions. In para 7, we find the procedure for determination in increase of production of an industrial unit which undertakes expansion/modernisation/diversification. In para 1OA and B, procedure have been prescribed with regard to raw materials and finished products so far they apply to the 'existing units'. A joint reading of the provisions of Industrial Policy of 1991 with the provisions of the Scheme 1995 as above prepared under the provisions of the Assam General Sales Tax Act, 1993, would show that the incentives promised to be given by the State in its Industrial Policy of 1991 have not been in any way taken away or restricted in any manner so as to prejudice the appellants. In fact, the scheme prepared in 1995 is in conformity with what have been spelt out in the policy decision of 1991. The scheme framed in 1995 under the provisions of the Assam General Sales Tax Act, 1993 and brought into force wef 1.4.1991 is in fact a legislative measure adopted to implement the Policy of 1991. The argument that the State has withdrawn the incentives declared in 1991 with retrospective effect is, therefore, of no significance. The scheme framed in 1995 under the provisions of the Assam General Sales Tax Act, 1993 and brought into force wef 1.4.1991 is in fact a legislative measure adopted to implement the Policy of 1991. The argument that the State has withdrawn the incentives declared in 1991 with retrospective effect is, therefore, of no significance. In my opinion, there is practically no difference in the promise made in the Industrial Policy of 1991 and the scheme prepared in 1995. The appellants being 'existing units' as defined in the Industrial Policy of 1991 have obviously no cause to vindicate. The policy decision of 1991 extended full sales tax exemption for 7 years to the new units while it conferred restricted benefits to the 'existing units' to the extent of expanded industrial activity only. That being the position, I am of the opinion that these appeals are devoid of merit and deserves dismissal." 6. Dr. AK Saraf, representing the industrial units, while supporting the view of Smti Meera Sharma, J, and while interpreting the Industrial Policy of 1991 and Scheme of 1995, has vehemently argued that the benefit of full sales tax exemption granted under 1991 Industrial Policy has been taken away by 1995 Scheme. He has interpreted 1991 Industrial Policy by arguing that in the Industrial Policy of 1991 sales tax exemption was granted to new industrial units set up as well as existing industrial units undertaking expansion/modemisation/diversification at the same location or at any other place in the State of Assam for a period of seven years. The precise argument of the learned counsel is that in clause 2 of Part II of 1991 Industrial Policy 'eligible units' have been defined and clause 3 talks of 'new units' set up on or after 1.4.91 and clause 4 defines an 'existing unit'. According to the counsel, it has been envisaged by clause 2 of 1991 Industrial Policy that both new as well as existing units shall be eligible for incentives under the scheme provided they fulfill the requirements of clause 2.1. It has further been argued that 'new units' have been defined in clause 3 whereas 'existing unit' has been placed on equal footing with the new units in view of the definition of clause 4. It has further been argued that 'new units' have been defined in clause 3 whereas 'existing unit' has been placed on equal footing with the new units in view of the definition of clause 4. The learned counsel has further argued that an industrial unit undertaking expansion/modernisation or diversification would also be eligible for all incentives provided the total capital investment is made by the industrial unit at least to the extent of 25% in the installed capacity and increase of additional employment at least by 10%. According to the counsel, this has been made clear by the wording of clause 5. It is further the argument of Dr. Saraf that the factum of the existing units availing the benefits of incentives would not disqualify the expansion/modernisation/diversification projects to get the incentives for the extra investment made. According to clause 6, the counsel submits that both new as well as existing units were entitled to full exemption of sales tax on purchase of raw materials as well as the sale of finished products for a period of seven years. The learned counsel, after reading the notification of 1995, that is, the Industrial Scheme of 1995, has submitted that a change has been made inasmuch as a mention has been made in clause 7 to the effect that the actual production of an industrial unit during 365 working days of the unit preceding the date of completion of its expansion/modernisation/diversification would be called its base year production. According to Dr. Saraf, clause 10A and 10B of Industrial Scheme of 1995 when read together, limit the right of the existing industrial unit to claim exemption between the actual production and base year production, which was not the position under the 1991 Industrial Policy. The learned counsel, in support of his argument, has relied upon the decision of the Hon'ble Supreme Court in State of Bihar vs. Suprabhat Steel Ltd, (1991) 1 SCC 31. 7. Lastly, Dr. Saraf has argued that even if there is ambiguity in the Industrial Policy of 1991 and the Scheme of 1995, a construction beneficial to the subject of the State should be adopted. In this context, another judgment of the Hon'ble Supreme Court in Commissioner of Income Tax, Patiala vs. Shahzada Nand and Sons & others, 60 ITR 393, has been relied upon. 8. Mr. In this context, another judgment of the Hon'ble Supreme Court in Commissioner of Income Tax, Patiala vs. Shahzada Nand and Sons & others, 60 ITR 393, has been relied upon. 8. Mr. BC Das appearing for the State of Assam has with equal vehemence argued that the Industrial Policy of 1991 and 1995 Scheme are not inconsistent with each other and that 1995 Scheme does not curtail the rights of the industrial units which were conferred under 1991 Industrial Policy. According to the counsel, the perusal of 1991 Industrial Policy clearly shows that only new industrial units set up on or after 1st April, 1991 and such units who undertook expansion, modernisation and diversification have been made eligible for exemption on fulfillment of certain conditions specified therein. The existing units according to Mr. Das, who undertook capital investment of plant and machinery in the expansion/modemisation/diversification to the tune of more than 25% of the total fixed capital investment are eligible for all incentives. Increase of additional employment at least by 10% is also another factor, according to him, which makes an existing unit eligible for availing the incentives. The precise argument of Mr. Das is that even those industrial units who have already availed the incentives, but are existing, they do not stand disqualified to get incentives, but they would get incentives only for the extra investments made and not for the entire unit; whereas a new industrial unit would get full sales tax exemption. According to the counsel, there is no departure from the aforesaid policy in the 1995 Industrial Scheme and that both the Industrial Policy of 1991 and Industrial Scheme of 1995 are in consonance with each other. It has further been argued by Mr. Das that the factum of the existing units getting full exemption from payment of sales tax under the old Industrial Policy of 1986 is also relevant for considering the object sought to be achieved of the public good at large by the Industrial Policy of 1991 and that it would be discriminatory and against public interest to give the industrial units full exemption under the 1991 Policy for another period of seven years. The decision of the Apex Court in the State of Bihar & others vs. Suprabhat Steel Ltd & others, relied upon by Dr. Saraf, has been distinguished by Mr. The decision of the Apex Court in the State of Bihar & others vs. Suprabhat Steel Ltd & others, relied upon by Dr. Saraf, has been distinguished by Mr. Das by arguing that the Apex Court on interpretation of clause 10.4 (i) (a) and (b) of the Bihar Industrial Incentive Policy, 1993, held that the benefit would not only be extended to old industrial units which started production between 1.4.93 and 31.3.98 but also to those industrial units which started production before 1.4.93. 9. As regards the decision of the Apex Court in Shahzada Nand's case (supra) reported in 60 ITR 392, Mr. Das submitted that the present is not a case where there is any ambiguity, the benefit of which should be given to the subject of the State. According to Mr. Das, no two interpretations are possible and, therefore, the ratio of law in Shahzada Nand's case (supra) is inapplicable to the facts of the present case. 10. I have given thoughtful and deep consideration to the respective arguments of the counsel for the parties. In my considered opinion, the answer to the arguments would lie in interpretation of the Policy of 1991 and Industrial Scheme of 1995. 11. Adverting to the interpretation of the Policy of 1991,1 need straightway refer to the definition of the words 'eligible unit' who is entitled to incentives mentioned in the policy. Eligible unit has been defined in clause 2. This clause clearly lays down that only new units which have been set up on or after 1st of April, 1991 and existing units undertaking expansion, modernisation or diversification, either at the same location or at any other place in the State of Assam, shall be eligible to avail of the incentives under 1991 Scheme provided they fulfil the conditions laid down in clause 2.1. New units as well as existing units have been placed on same footing in accordance with clause 2 of the Policy of 1991. As to what is a new unit, the same has been defined in clause 3 of the aforesaid policy. That industrial unit, according to clause 3, would be called a 'new unit' which has taken all initial effective steps on or after 1 st April, 1991. Existing unit has been defined as the one for the purpose of 1991 Scheme which had come up for commercial production at any time before 1st April, 1991. That industrial unit, according to clause 3, would be called a 'new unit' which has taken all initial effective steps on or after 1 st April, 1991. Existing unit has been defined as the one for the purpose of 1991 Scheme which had come up for commercial production at any time before 1st April, 1991. Clause 5 envisages that existing industrial units would also be eligible for all incentives provided expansion/modernisation/diversification has been undertaken by such an existing industrial unit by investing capital of more than 25% of the total fixed capital investment It has again been so stated in clause 5 that expansion/ modernisation/diversification would simply an increase of at least 25% in the existing installed capacity as well as increase of additional employment at least by 10%. Use of specific words "industrial unit will also be eligible for all incentives...." clearly shows that an existing industrial unit would also (emphasis supplied) be eligible for all incentives, provided there is an increase in capital investment on plant and machinery. The phraseology of the words and more particularly the word 'also' mentioned above clearly denotes that an existing unit has been placed on equal footing asregards availing of incentives is concerned. This position has further been strengthened by sub-para of clause 5, which clearly says that the factum of the existing unit availing itself of incentives, the same would not disqualify the expansion/modernisation/diversification project to get incentive for the extra investment made. Clause 6 of the Policy of 1991 clearly says that sales tax will be exempted on purchase of raw materials and sales of finished products for a period of seven years. This clause is mandatory as the word 'will' has been used therein. Sales tax exemption has been granted both on purchase of raw materials and sales of finished products by an industrial unit. In other words, an existing industrial unit would not be liable to pay sales tax on purchase of raw materials and shall also be not liable to pay sales tax on finished products for a period of seven years. May be the words 'full sales tax' have not been used in clause 6, but the use of the word 'sales tax exemption' would necessarily mean total exemption from payment of sales tax by an existing industrial unit. 12. May be the words 'full sales tax' have not been used in clause 6, but the use of the word 'sales tax exemption' would necessarily mean total exemption from payment of sales tax by an existing industrial unit. 12. Whether each clause of Policy of 1991 is interpreted in its isolation or all the clauses are put together, the interpretation, in my considered opinion, would be that both new units and existing units are eligible to avail of sales tax exemption limit in its entirety whether it be on purchase of raw materials or sales of finished products. 13. The aforementioned interpretation put by me upon the Industrial Policy of 1991, leads me to scrutinise, whether any change has been made by the notification of 1995 in Industrial Scheme of 1995 has been published. Clause 7 laid down the criterion of actual production of an industrial unit during 365 consecutive working days preceding the date of completion of its expansion by describing the same as base year production. This was the criterion in the Industrial Policy of 1991. There not even a single word in clause 7 to the effect that existing unit would also be eligible for all incentives, namely, sales tax exemption, provided it undertakes expansion/modernisation/diversification by making an increase of at least 25% in the existing installed capacity as well as increases of additional 10% employment. On the other hand, altogether different criterion has been laid down not only in clause 7 but in other clauses as well which have been reproduced by me in the earlier part of my judgment i.e. paragraph 3. In my considered opinion, it is too much for the State now to contend that sales tax exemption would be available to an industrial unit to that extent only to which expansion was made by an industrial unit, after having held out a promise in the year 1991 that sales tax exemption shall be available to both new and existing industrial units. It would not be out of place to mention at this stage that it is the specific case of the appellants that they neither paid sales tax on the purchase of raw materials nor charged sales tax on finished goods. Not only that even implementing agency, admittedly, issued Eligibility Certificates to all the appellants granting them exemption from payment of sales tax for a period of seven years. Not only that even implementing agency, admittedly, issued Eligibility Certificates to all the appellants granting them exemption from payment of sales tax for a period of seven years. No condition whatsoever was laid down in the certificates that the exemption would be available only on the increase in production resulting from the expansion, modernisation or diversification and in fact, no provision in the Industrial Policy of 1991 contemplated about the increase in production for availing the full sales tax exemption. In other words, the Industrial Policy was understood both by the industrial units and by the department in the same manner. It is now too late in the day to ask the industrial units to pay the sales tax beyond the increased capacity when they have neither paid the same on raw materials purchased nor charged the same on finished goods from their customers. 14. It appears to me that full sales tax exemption was granted even to the existing industrial units keeping in view the peculiar conditions prevailing in Assam where, it cannot be denied, that industries have gone to dogs. It appears to me that in order to boost up the setting up of new industries and also to boost up the expansion, modernisation and diversification of existing industrial units that exemption from payment of sales tax was granted for a period of seven years. After making a clear cut provision in the 1991 Policy, the State cannot take a somersault and change the scheme in the year 1995 to the detriment of its subjects. 15. Since the decision in these cases has been arrived at by me by interpreting the Policy of 1991 and Industrial Scheme of 1995, there is no need to go into the question whether the judgment of the Apex Court in State of Bihar & others vs. Suprabhat Steel Ltd & others (supra) is applicable or not since I am further of the view that the interpretation placed by me is the only possible interpretation and no other interpretation is possible. I hold that there is no ambiguity in the Policy of 1991. I hold that there is no ambiguity in the Policy of 1991. However, even if it be assumed for a moment that there is ambiguity in the language in the 1991 Policy, its benefit must go to the subject of the State, as has been held in the case of Commissioner of Income Tax, Patiala vs. Shahzada Nand and Sons & others (supra). 16. Although the arguments of the counsel for the State pale into insignificance in the light of the observations made by me in the above paragraphs, yet it would be appropriate to deal with the submissions of the State counsel. I am unable to agree to accept the argument of Mr. Das that the Industrial Policy of 1991 and 1995 Scheme are not inconsistent with each other and that 1995 Scheme has not curtailed the rights of the industrial units which stood conferred under 1991 Industrial Policy. As has been observed above, the Industrial Policy of 1991 did contemplate in clear and unequivocal words that sales tax exemption would be available even to the existing units and that the same would be at par with the new units. But 1995 Scheme has limited the rights of existing industrial units to the extent of expansion. Even the wording of all the clauses of 1995 Scheme is altogether different and inconsistent with 1991 Industrial Policy and, therefore, it cannot be maintained successfully by the counsel for the State that there was no departure in Industrial Scheme of 1995. Equally untenable is the argument of Mr. Das that the very fact that the existing units got full exemption from payment of sales tax under old Industrial Policy of 1986, it would be discriminatory and against public interest to give full exemption again in the year 1991 for another seven years and that the object sought to be achieved would be against public good at large. The Government cannot be estopped to confer the benefit of exemption from payment of sales tax simply because a similar benefit was granted earlier. As has been observed above, the object of granting full sales tax exemption to the existing as well as new industrial unit seems to be to boost up industrial development and generation of adequate employment opportunities. The Government cannot be estopped to confer the benefit of exemption from payment of sales tax simply because a similar benefit was granted earlier. As has been observed above, the object of granting full sales tax exemption to the existing as well as new industrial unit seems to be to boost up industrial development and generation of adequate employment opportunities. The very fact that the provision for more employment is there in 1991 Industrial Policy, it shows that the Government intended to confer the benefits even upon existing industrial units in the same manner as upon new units. In view of the discussion, I agree with the view expressed by Meera Sharma, J. may be with some additional reasoning. As a consequence thereof all writ appeal shall stand allowed.