T. L. VISWANATHA IYER, J. - These original petitions are filed by oil millers who feel aggrieved by a part of the Notification S.R.O. No. 781 of 1989 issued by the Government on May 18, 1989, under section 10 of the Kerala General Sales Tax Act, 1963. The notification has been given retrospective effect from July 1, 1987. The notification has ceased to be in effect on March 31, 1992. To understand the grievance of the petitioners, it is necessary to state the history of the reduction in the rate of purchase/sales tax relating to coconut, copra, coconut oil and coconut oil-cake over the years. The statute concerned is the Kerala General Sales Tax Act, 1963 (hereinafter referred to as "the Act").

2. Petitioners are all oil millers who purchase coconut and copra, for crushing in their oil mills, and sell the resultant oil and oil-cake produced out of such coconut or copra either within the State or in the course of inter-State trade. Coconut and copra constitute entry No. 6 in the Second Schedule to the Act, liable to tax at 4 per cent at the point of last purchase. Similarly coconut oil and oil cake were entries 60 and 29, respectively in the First Schedule to the Act up to