1. The appeal is directed against the judgment in O. P. No. 337 of 1970. The question raised in the writ petition was regarding the constitutionality of differential rates of levy or water-tax in the Mattancherry and the Ernakulam areas both of which are comprised in the limits of the Corporation of Cochin, which was formed on and from 1-11-1967. In the Mattancherry area of the Corporation, water-charges are levied at the rate of Rs. 8/- per 1000 gallons for non-domestic use; and in the Ernakulam area, at the rate of Rs. 3/ - per 1000 gallons for non-domestic use. We need not enter into the further details of the levy as the learned Single Judge has held the levy to be unconstitutional as discriminatory and no appeal against the said judgment has been filed by the Corporation.

2. The only grievance of the petitioner is against the learned judge having confined the relief granted to the petitioner from the date of pronouncing judgment on the theory of what the learned judge described as "prospective overruling". This is what the learned judge stated:

"9. I think that this is an eminently proper case for applying the doctrine of prospective over-ruling recognised and applie