In support of the petition, the learned counsel for the petitioners has raised the following contentions: (1) that the transactions in respect of which the petitioners are sought to be taxed are not covered by the explanation to section 2(g) of the Bengal Finance (Sales Tax) Act, as extended to Delhi; (2) alternatively, that is to say, if it is held that the explanation covers the transactions of the nature aforesaid, then the explanation, extending the concept of 'sale ' is unconstitutional; (3) That in any case it is unconstitutional as it infringes article 14 of the Constitution in so far as the State of Delhi has been selected for hostile discrimination; (4) that the judgment of the Punjab High Court in Installment Supply Ltd., New Delhi vs State of Delhi (1) is final and conclusive as between the parties to that judgment; (5) that if it is held that the judgment of the Punjab High Court, referred to above, has been superseded by the judgment of this Court in Mithan Lal 's case (2), that judgment cannot be given retrospective operation; and (6) lastly, that the settlement between the Department and the Companies transacting business in "Hire purchase" is binding until the decision of this Court in Mithan Lal 's case (3), aforesaid.