RAJAGOPALAN, J.

The plaintiffs-appellants were building contractors. For the assessment years 1948-49 to 1952-53 the appellants were assessed to sales tax under the Madras General Sales Tax Act on the turnover of their works contracts computed in accordance with the rules framed under that Act. Subsequently, in Gannon Dunkerley's case this Court held that the legislative provision in the Sales Tax Act for treating works contracts as involving taxable sales was ultra vires the legislature and that there was therefore no valid legislative sanction for taxing the turnover of such works contracts with reference to buildings. That was confirmed by the Supreme Court in State of Madras v. Gannon Dunkerley and Co. After the declaration of the law on the validity of the legislative provision to the works contracts by this Court, the plaintiffs instituted the suit, out of which this appeal arises, for recovery of the amounts paid by them for the assessment years we have referred to above. That claim was resisted by the State.

The learned trial Judge upheld the pleas of the defendant State. The learned Judge upheld the claim that section 72 of the Indian Contract Act did not authori