( 1 ) PETITIONERS are different; but the questions of law raised are common; hence these two writ petitions have been heard together and are being disposed of by this judgment.

( 2 ) IT would suffice to state the facts in W. P. No. 2121 of 1987 for deciding the questions of law raised. The petitioner is a civil engineering contractor having its office at Madras. For the time being, it has civil engineering contracts with Department of Space, Government of India, at Sriharikota, Nellore district, in the State of Andhra Pradesh. As the petitioner did not trade in any goods, it did not get itself registered earlier as a dealer under the Andhra Pradesh General Sales Tax Act, 1957 ("apgst Act" ). The petitioner, however, got itself registered and obtained a registration with effect from 1/07/1985 on which date the Andhra Pradesh General Sales Tax (Amendment) Act (Act 18 of 1985) came into force, inasmuch as under the said Act transfer of property in the goods used in execution of works contract was made liable to sales tax. This amendment of the "apgst Act" was in consequence of the Constitution (Forty-sixth Amendment) Act. which came into force on 3/02/1983, necessitat