Judgment :- MOHAN, J. Suit for refund of a sum of Rs. 51, 954.36, being Rs. 43, 659.15 with interest thereon at 6 per cent per annum from 18th January, 1969. The plaint allegations, inter alia, are as follows : The plaintiff is a dealer in engineering equipments and act on behalf of their principals, Messrs. Alfred Herbert (India) Private Limited, for goods imported under the import trade control permit issued to various customers. As the plaintiff's principals were importing and supplying the goods, the Controller of imports permitted the customers to authorise the plaintiff's principals to import the goods on their behalf. According to the terms arrived at between the parties, the plaintiff's principals are entitled to payment of the price of the goods supplied and the sales tax in full when they presented the invoice for the goods. All such transactions are sales effected in respect of goods imported on actual user's licence obtained by the customers from the Chief Controller of Imports and Exports and letters of authority given to the plaintiff's principals to import the goods. The transactions were taxed by the first defendant as local sales for the assessment year up to 1966-67. For the said assessment year, the second defendant passed the assessment order MGST 431/66-67 on 15th March, 1968, including a turnover of Rs. 17, 46, 368.59 as taxable under the provisions of the Tamil Nadu General Sales Tax Act. This turnover represents sales in the course of import, and it would be covered by the ratio of the decision laid down in K. G. Khosla and Co. (P.) Ltd. v. Deputy Commissioner of Commercial Taxes The Supreme Court delivered the judgment on 18th January, 1966, and it was actually reported on 1st May, 1966, in the Law Journals. On 14th October, 1968, the third defendant wrote to the plaintiff stating that these transactions would fall within the decision of the Supreme Court. Thereupon the plaintiff filed Writ Petition No. 3544 of 1969 (Parry & Co. Limited v. The State of Madras to direct the sales tax authorities to investigate the character of the transactions in the light of the Supreme Court decision and also to refund the sum of Rs. 43, 659. On 23rd November, 1971, the writ petition was dismissed. Thereupon the plaintiff filed Writ Petition No. 3544 of 1969 (Parry & Co. Limited v. The State of Madras to direct the sales tax authorities to investigate the character of the transactions in the light of the Supreme Court decision and also to refund the sum of Rs. 43, 659. On 23rd November, 1971, the writ petition was dismissed. Consequently, the present suit has been filed, claiming refund on the ground of mistake of fact and mistake of law.The defence taken by the first defendant and the second defendant is that the suit is not maintainable in law and more so in view of the provisions of section 51 of the Tamil Nadu General Sales Tax Act, 1959. This apart, the facts of this case differ from the facts of the decision in K. G. Khosla and Co. (P.) Ltd. v. Deputy Commissioner of Commercial Taxes. It is also submitted that the plaintiff preferred an appeal to the Appellate Assistant Commissioner, and in the appeal, it did not dispute the liability to tax on the turnover now in dispute. Nor were any materials placed before the concerned tax authorities to decide this question. Therefore, it cannot be contended that the plaintiff has committed any mistake. Nor can it be said that the assessment order is ultra vires. Inasmuch as the assessment order has become final, the same cannot be challenged in an indirect way by filing the suit. Hence the suit is liable to be dismissed. The defendants 3 and 4 have filed a common written statement, setting out the nature of the transactions. According to them, in view of the decision of the Supreme Court, the State is prohibited from imposing the sales tax on the sale or purchase of goods, where such sales take place in the course of import of the goods into the territory of India. The plaintiff should contest the liability to sales tax only with the Tamil Nadu Government. These defendants do not admit that the plaintiff discovered the mistake only from the third defendant on 14th October, 1968. The plaintiff is barred from maintaining the suit, having already filed a writ petition. Inasmuch as no reservation has been made for any relief to be pursued against the defendants, the suit is barred. On these pleadings, the following issues have been set down for trial :1. The plaintiff is barred from maintaining the suit, having already filed a writ petition. Inasmuch as no reservation has been made for any relief to be pursued against the defendants, the suit is barred. On these pleadings, the following issues have been set down for trial :1. Whether the transactions in question are in the course of import ? 2. Whether the plaintiff is estopped from questioning the legality of the assessment order in so far as it relates to the disputed turnover ? 3. Whether the plaintiff is entitled to refund of the tax levied and collected under the relevant provisions of the Tamil Nadu General Sales Tax Act, 1959, even though the plaintiff has allowed the assessment to become final by not challenging the same before the appropriate statutory authorities ? 4. Whether the plaintiff is entitled to any interest ? 5. Whether the suit is not maintainable in law ? 6. Whether this court has no jurisdiction to try this suit 7. Whether the plaintiff has cause of action to file this suit ? 8. Whether the suit is barred by limitation ? No oral evidence has been let in, and the parties were content in marking the documents. Exhibits P-1 to P-4 were marked on the side of the plaintiff, and exhibits D-1 and D-2 were marked on the side of the defendants. Issue No. 5 - It is contended by the learned Government Pleader appearing for the defendants 1 and 2 that the suit is not maintainable in view of the express bar contained in section 51 of the Tamil Nadu General Sales Tax Act, 1959. In support of this contention, two decisions are cited before me. One is Kamala Mills Ltd. v. State of Bombay, in which the Supreme Court in dealing with a similar case arising out of the Bombay Sales Tax Act, 1946, held : "Under the Bombay Sales Tax Act, 1946, the appropriate authorities have been given power in express terms to examine the returns submitted by the dealers and to deal with the question as to whether the transactions entered into by the dealers are liable to be assessed to sales tax under the relevant provisions of the Act or not. All questions pertaining to the liability of the dealers to pay assessment in respect of their transactions are expressly left to be decided by the appropriate authorities under the Act as matters falling within their jurisdiction..............If the appropriate authority, while exercising its jurisdiction and powers under the relevant provisions of the Act, holds erroneously that a transaction, which is an outside sale, is not an outside sale and proceeds to levy sales tax on it, it cannot be said that the decision of the appropriate authority is without jurisdiction." * In a case decided by this court, in State of Madras v. Ramakrishna Mills (Coimbatore) Ltd. under similar circumstances, it was held as follows : "(1) The sales tax authority has jurisdiction to decide whether a transaction of sale or purchase takes place within the State of Madras. In the same category will fall a decision as to whether a sale or purchase takes place outside the State or in the course of inter-State trade or commerce or in the course of import or export attracting the bar under article 286 of the Constitution. These questions involve a decision of fact as well as of law and they are within the exclusive jurisdiction of the sales tax authority. Even if the sales tax authority arrives at an erroneous decision on these points, the remedy of the aggrieved party is the remedy provided in the Sales Tax Act, by way of appeals and revision to the High Court. The effect of section 18-A of the Madras General Sales Tax Act, 1939, is that the aggrieved party cannot by-pass these provisions and seek remedy by way of suit under the common law, and urge that what has been paid by him is one paid under a mistake of fact and law and, therefore, refundable under the general principle stated in section 72 of the Indian Contract Act. (2) Under the scheme of the Sales Tax Act, the assessing authority is also given power to decide the jurisdictional question, which arises in such cases, namely whether a sale takes place inside the State, in which event alone the sales tax authority of the State has got jurisdiction to assess it; or whether a sale takes place outside the State or in the course of inter-State trade or commerce or in the course of import or export, in which case, under article 286 of the Constitution, the Sales Tax Officer of the State loses the power to assess the transaction. It is erroneous to hold that the moment a question of jurisdiction in this sense is raised, in assessment proceedings, the issue falls outside the purview of the sales tax authority, and should be agitated in a separate suit." * I may only state that section 18-A of the Madras General Sales Tax Act, 1939, was similarly worded as section 51(1) of the present Act. In meeting these contentions, the learned counsel for the plaintiff firstly relies on Venkataraman & Co. (P.) Ltd. v. State of Madras.