The court confirmed plaintiffs' entitlement to refund of mistakenly paid sales tax based on the principles of unjust enrichment, affirming jurisdiction and time applicability under the Limitation Act.

1. These revision petitions arise out of suits filed by the various plaintiffs, respondents in each of the revision petitions, for recovery of amounts collected from them by the defendants in each of the suits as Central sales tax in respect of certain sales of arecanuts effected by the defendants to the plaintiffs who are dealers at Thiruvarur, Madras State. As all the above revision petitions raise the same question of law, they have to be dealt with together.

2. The defendant in each of the suits is dealer in arecanuts at Shimoga in Mysore State. They have been selling arecanuts to the plaintiffs during the years 1961 to 1964. The defendants as sellers have been charging and collecting Central sales tax from the plaintiff on their sales of arecanuts on the basis that the transactions were inter - State sales attracting the levy of sales tax under the Central Sales Tax Act. 1956. The tax thus collected has been shown separately in the various invoices issued by the defendant in each of the suits. The sales tax collected by the defendants from the plaintiffs had been originally remitted by the defendants to the Mysore Sales Tax Authorities. Subsequently, the Supreme Court on 10-11-1964, held in State of Mysore v. Y.L. Setty and Sons . 1965-2 SCR 129 : (AIR 1965 SC 1510), that though S.6 of the Central Sales Tax Act is the charging section, the liability to pay tax is subject to the other provisions of the Act, that S.9(2) provides that tax shall be calculated at the same rates and in the same manner as would have been done if the sale had in fact taken place inside the appropriate State, that, the tax under the Central Act shall be levied in the same manner as the tax on the sale or purchase of goods, under the general sales tax law of the State is assessed, paid and collected, and that, therefore, if no tax was exigible in respect of the same transactions under the Mysore Sales Tax Act no tax was payable under the Central Act Belying on the said decision, the sales tax authorities of Mysore State refunded the tax collected on inter - State sales of arecanuts to the defendants in or about 1967. The plaintiffs who became aware of the said refund of the tax have filed various suits in the year 1969 for recovery of the amounts paid by them as sales tax from the defendants. According to them the Central sales tax has been paid by them under a mistaken impression that the Central sales tax was leviable on the inter - State sales of arecanuts by the Mysore dealers. However, with a view to get over the decision of the Supreme Court referred to above, the "Central Sales Tax (Amendment) Act 1969" (Central Act 28 of 1969) had been enacted by the Parliament under which S.9 of the Principal Act was amended with retrospective effect so as to enable the levy of tax on Inter - State sales whether such sales are exigible to tax in the concerned State or not and all the assessments made already had been validated notwithstanding any decree or order of any court to the contrary.

3. The defendants had resisted the suit on various grounds. One of the grounds raised was that they did not get any refund of the tax from the sales tax authorities. But the trial court did not accept that plea but held that on consideration of the evidence the defendants had got refund of the sales tax paid by them from the sales tax authorities in pursuance of the decision of the Supreme Court referred to above. In these revisions the factum of refund of tax was not disputed before us.

4. The other defences taken were (1) that the suits are barred by limitation as they have been filed more than 3 years after the payment of the tax; (2) that the trial court had no jurisdiction to try the suits an