“69. However, while widening the scope of entry 54 of List II, the powers of the State to levy such tax are subjected to a corresponding restriction as a consequence of the constitutional curbs imposed on sales tax under article 286 read with sections 14 and 15 of the Central Sales Tax Act, 1956, and the ADE Act, 1957. “The tax leviable by virtue of sub-clause (b) of clause (29A) of article 366 of the Constitution thus becomes subject to the same discipline to which any levy under entry 54 of the State List is made subject to under the Constitution. The position is the same when we look at article 286 of the Constitution. If any declared goods which are referred to in section 14 of the Central Sales Tax Act, 1956, are involved in such transfer, supply or delivery, which is referred to in clause (29A) of article 366, the sales tax law of a State which provides for levy of sales tax thereon will have to comply with the restrictions mentioned in section 15 of the Central Sales Tax Act, 1956”.