All these writ petitions can be dealt with under a common judgment since they question the validity of section 5B of the Karnataka Sales Tax Act, 1957, introduced by the Amendment Act No. 27 of 1985, with effect from 1st April, 1986.

2. We propose to note the facts in Writ Petitions Nos. 2064 to 2067 of 1988 :

The petitioners are civil engineering contractors engaged in civil construction work in the State of Karnataka. In order to bring the activity of works contract within the purview of power to levy sales tax by the respective State, amendments were introduced extending the definition of "sale" under article 366(29-A) of the Constitution of India. Following the constitutional amendment, the Karnataka Sales Tax Act was amended by the Amendment Act No. 27 of 1985. In pursuance of the amendment, the Karnataka Sales Tax Rules were also amended by the Karnataka Sales Tax (Amendment) Rules, 1986.

As a result of the aforesaid amendments, the activity of the petitioner in the nature of works contract in the State, has been brought within the scope of the Karnataka Sales Tax Act.

The petitioners challenge the constitutionality of the Forty-Sixth amendment, as well as the amendm