delivered the opinion of the Court.

In 1947 Pedro A. Pizá, Inc. sold two trucks which it had in stock to Ochoa Fertilizer Corporation at a price which included the excise tax. Pizá paid the tax to the Treasurer as required by law.1 Ochoa petitioned the Treasurer for refund of the tax on the ground that it was exempt from taxation, see Buscaglia Treas. v. Tax Court, 66 P.R.R. 670. The Treasurer denied the petition. His position was that the taxable event was introduction of the trucks into Puerto Rico; that introduction was effectuated by Pizá and not by Ochoa; and that Ochoa’s exemption would apply herein only if it were the “efficient importer”. Suit for refund was filed in the Tax Court by Pizá, for the benefit of Ochoa. The Tax Court dismissed the case for lack of jurisdiction pursuant to Act No. 137, Laws of Puerto Rico, 1945. We granted certiorari to review this decision.

*304 We do not stop to determine whether this suit should have been brought by Ochoa or by Pizá. Construing the pleadings liberally, we interpret them as bringing both corporations before the court. Also, we need not pass on the contention of the Treasurer that under § 16(8) of the Internal Revenue Law2 the taxable event here was introduction into Puerto Rico of the trucks by Pizá.3 For purposes of this case, we assume, without deciding, that the first taxable event was the sale of the trucks by Pizá to Ochoa. But even under this assumption, Pizá rather than Ochoa was the taxpayer. As we pointed out in Porto Rico Telephone Co. v. Tax Court, 68 P.R.R. 144, 153, “In examining our sales tax, we find that it is imposed legally on the vendor. Unlike the situation in some states, the vendor is neither forbidden nor required to add the tax to the sales price. He is left free to do as he chooses.”4

Since Pizá was legally liable for the taxes herein, it follows that the Tax Court was correct in holding that it lacked jurisdiction in this case by virtue of § 4 of Act No. 169, Laws of Puerto Rico, 1943, as amended by Act No. 137, Laws of Puerto Rico, 1945.5 As we pointed out in Standard Commercial Tobacco Company, Inc. v. Tax Court, 71 P.R.R. 701, § 4 establishes two prerequisites for jurisdiction of the Tax Court: (1) the suit must be by the taxpayer; (2) the plaintiff must have in fact suffered the economic burden of the tax. Neither *305Pizá nor Ochoa meets both of these tests. Pizá was the taxpayer, but it passed the burden of the tax on to Ochoa. And although Ochoa suffered the burden of the tax, it was not the taxpayer.

The petitioners argue that the Legislature meant to provide in Act No. 137 that any person who had suffered the economic burden of an excise tax, whether or not he was the taxpayer, could sue in the Tax Court. We rejected this argument in the Standard Commercial case and do so again. For it to prevail we would have to hold that' in enacting this statute the Legislature intended to enlarge the jurisdiction of the Tax Court. Under this theory, if an excise tax imposed by law on the first vendor should eventually be held invalid, any ultimate consumer, no matter how remote, of all sorts of merchandise could sue in the Tax Court if he could show that the tax had finally been passed on to him as part of the purchase price. We are satisfied that the Legislature did not intend to enlarge the jurisdiction of the Tax Court in this manner. On the contrary, the purpose of Act No. 137 was to restrict the jurisdiction of the Tax Court in order to prevent unjust enrichment. The Legislature foresaw the possibility that some taxpayers might receive a windfall because a particular excise tax had been declared invalid years after the taxpayers on whom the taxes were imposed by law had paid them and had passed the burden thereof to their *306vendees.6 It therefore closed the doors of our courts to such cases.7 Only taxpayers who had absorbed the taxes and had not passed them on to their vendees could sue therefor.8

It remains to note one argument with reference to Act No. 137. The petitioners contend that it does not apply to this suit for refund inasmuch as it provides that it shall apply “When the case concerns a demand for payment made by the Treasurer . . To agree with this argument would be to hold that the Legislature meant to grant jurisdiction when the taxpayer paid pursuant to demand by the Treasurer but not voluntarily. We think the Legislature intended no such discrimination. The explanation Is simple. Act No. 137 was passed at a time when the Legislature and the Treasurer were both under the impression that suits for refund of excise taxes would lie only if they had been paid under protest after a demand by the Treasurer. The Legislature therefore obviously intended that all suits for refund of excise taxes' must conform to the requirements of Act No. 137. It mentioned a demand for payment by the Treasurer only because of its impression that those were the only suits which could be brought at that time. Thereafter, we held that a suit for refund would lie even after voluntary payment without demand. Gerardino v. Tax Court, 68 P.R.R. 206, 210, and cases cited. Despite the literal language of Act No. 137, we therefore believe, in view of the foregoing sequence of events, that the Legislature intended for Act No. 137 to apply to all suits for refund of excise taxes, including the instant case *307where the payment was voluntarily made without a demand by the Treasurer.

Relying on West India Oil Co. v. Tax Court, 65 P.R.R. 70, the petitioners assert that they are entitled to prevail on the merits. The Treasurer, on the other hand, strenuously argues that the West India ease was wrongly decided and should be reversed.9 We never reach this question as neither the Tax Court nor this Court has jurisdiction in this case.

We recognize that the practical effect of Act No. 137 is to close the doors of the courts to any attempt to enforce the rights of a tax-exempt vendee under the circumstances of this case, without reference to whether the West India case was erroneously or correctly decided. And such a vendee is unlikely to obtain from the Treasurer without judicial action a refund of a tax paid by the vendor and charged to the ven-dee as part of the purchase price, as the Treasurer has consistently maintained that the West India case is erroneous. However, there may be ways in which a vendee exempt from excise taxes may make his exemption economically effective. Cf. Buscaglia, Treas. v. Tax Court, 66 P.R.R. 670, 679. In any event, what relief, if any, should be provided for tax-exempt vendees under the circumstances herein is a matter for the Treasurer and the Legislature to determine. The only question before us is one of jurisdiction. And the courts are foreclosed from action by Act No. 137.

The decision of the Tax Court will be affirmed.