R. M. SAHAI, J. Manufacturers of galvanised iron pipes and tubes approached this Court by way of these petitions either against notices issued under section 21 of the U. P. Sales Tax Act, 1948, for reassessment or under rule 41 (5) or under rule 41 (7) of the Rules framed under the Act at the stage of provisional and final assessment. In some cases over assessments have been made; therefore, validity of assessment orders and recovery have been challenged. Dispute is if galvanised steel tubes and pipes are taxable as unclassified item under the U. P. Sales Tax Act or they being declared commodity under the Central Sales Tax Act are liable to tax at 4 per cent. Steel pipes and tubes undisputedly are declared commodity under the Central Sales Tax Act, 1956. In Gujarat Steel Tubes Ltd. v. State of Kerala [1989] 74 STC 176; (1989) 2 JT 474 , the Honourable Supreme Court after examining decisions given by various High Courts held that, "galvanised pipes are steel tubes within the meaning of section 14 (iv) (xi) of the Central Sales Tax Act". Therefore, the galvanised iron pipes and tubes are nothing but steel pipes and tubes which are declared commodity and as such are taxable at 4 per cent. They cannot be treated as unclassified item. But before parting with these petitions, we are constrained to observe that the Sales Tax Commissioner, acted not only beyond his powers as are visualised in sub-rule (2) of rule 4 of the U. P. Sales Tax Rules but was guilty of impropriety in issuing two circulars directing assessing authorities to assess the turnover of galvanised pipes as unclassified item even though this Court held otherwise. It was tantamount to issuing directions to subordinate authorities not to follow the law as declared by this Court forgetting that, every authority exercising judicial or quasi-judicial powers is under the supervisory jurisdiction of this Court under article 227 of the Constitution. The interpretation given by this Court of a notification, rule or law is binding on all authorities subordinate to it. The rule of finality arises both because of rule of law which is the basic foundation of our social system and the constitutional inhibition. The interpretation given by this Court of a notification, rule or law is binding on all authorities subordinate to it. The rule of finality arises both because of rule of law which is the basic foundation of our social system and the constitutional inhibition. Since the circular appeared to interfere with course of justice, notices under article 215 were also issued to the Commissioner, who in consequence thereof, withdrew the circular and filed an affidavit tendering apology. With the withdrawal of circular the necessity to examine its validity does not survive. And in view of affidavit the notice is discharged. In the result all the petitions succeed and are allowed. Notices issued either for reassessment or provisional or final assessment treating galvanised pipes as unclassified item are quashed. Similarly assessment orders and recoveries in pursuance thereof to the extent they relate to galvanised pipes assessed as unclassified item, are quashed. In other matters such as where proceedings are pending after remand or in respect of recognition certificate, etc. , the authorities are directed to proceed treating galvanised pipes as declared commodity and not as unclassified item. Althrough each petitioner is entitled to its costs but the petitions having been decided together, the costs are made easy. Petitions allowed. .