JUDGMENT

B.P. Jeevan Reddy, J.-Leave granted.

2. Ashok Leyland Limited, the appellant herein,* is one of the major manufacturers of trucks and other motor vehicles in India. Its registered office is at Madras (Chennai). The plants manufacturing trucks and motor vehicles are situated in the State of Tamil Nadu as well as in other States. The trucks and vehicles manufactured by it are sold all over the country. For its business purposes, it maintains Regional Sales Offices (R.S.Os.) in different parts of the country like, Bangalore, Trivandrum, Vijayawada, Pune, Nagpur, Indore, Calcutta, Bhuvaneshwar, Gauhati, Pondicherry and so on. The appellant says that each of these R.S.Os. maintains an office, a stock yard and other necessary paraphernalia for receiving , stocking, repairing and delivering motor vehicles to their customers. The appellant says that almost seventy percent of its sales are to parties other than State Transport Undertakings (S.T.Us.). The sales to S.T.Us. are in the region of thirty percent of its production. The R.S.Os., the appellant says, contact the local purchasers and the S.T.Us., book the orders and also deliver the vehicles to them pursuant to sales effected by them. The appellant always keeps the R.S.Os. well stocked having regard to their requirements. By way of illustration, it is stated, the R.S.O. at Hyderabad receives vehicles from Tamil Nadu from time to time. In respect of vehicles sold in Andhra Pradesh - whether to Andhra Pradesh State Road Transport Corporation or to other parties - sales tax is levied and collected by the State of Andhra Pradesh inasmuch as they are intra-State sales for the purpose of the Andhra Pradesh General Sales Tax Act. Over the years, the appellant says, it has been sending the trucks, chassis and other vehicles to R.S.Os. all over the country under F Form and at no time was the correctness of the F Forms produced by it questioned by any one. However, the State of Tamil Nadu has been seeking, in the recent times, to reopen the concluded assessments contending that the transfer of vehicles from Tamil Nadu to other States was not mere consignments (without effecting sales) but constitute inter-State sales within the meaning of clause (a) of Section 3 of the Central Sales Tax Act, which are taxable in the State of Tamil Nadu by virtue of the provisions of the Central Sales Tax Act. The attempt of the State of Tamil Nadu is to treat the said movement of vehicles as inter-State sales and tax them which would ultimately go back to that State by virtue of the provisions contained in Articles 269 and 286 of the Constitution and the Central Sales Tax Act. The appellant says that it did not effect any inter-State sales and that there was only one sale in the other State which has already been taxed under the sales tax law of that other State. The appellant complains that the same transaction cannot be taxed twice, once as an intra-State sale by one State and again by the State of Tamil Nadu as an inter-State sale. The appellant complains that the reopening of assessments - in some cases, even the re-assessment has been made and Central sales tax levied - and taxing the same transaction once again (by the State of Tamil Nadu) is causing serious harassment to the appellant, making it impossible for it to carry on its business operations in a smooth and orderly manner. It approached the Madras High Court with the said grievance. Though a number of factual issues were also raised in the writ petitions filed by the appellant, it was stated by their counsel at the time of hearing that they do not propose to invite the decision of the High Court on these factual issues and that they would be confining their submissions only to the questions of law, viz., the interpretation of Section 6-A of the Central Sales Tax Act and the power to reopen the orders accepting F Forms. In certain other writ petitions filed by the appellant, several State governments were impleaded as