The plaintiff company challenges the validity of the Business Franchise (Petroleum) Act, 1974-1975 S.A.. That Act had a short life. It came into operation in December 1974 and was repealed on 24th December 1975. In the meantime it had been amended. It is unnecessary for present purposes to distinguish between the unamended and the amended form of the Act; reference need only be made to the latter. The Act made it unlawful for any person to carry on the business of selling petroleum products on and from 24th March 1975 unless he was the holder of a licence: s. 11 (1). If a person was convicted of an offence against that provision, the court was required to impose upon him a penalty which included such amount (if any) as had been certified by the Commissioner as the amount by which the convicted person had benefited financially through non-payment of licence fees: s. 11 (1a). There were nine classes of licences: s. 12; the class of licence required depended mainly on whether the products to be sold were, or included, products manufactured by the licensee and whether the intended buyers were, or included, other licensees: see the definitions in s. 4 (1). An ordinary retailer of petrol from a service station required a class 9 licence, which authorized the licensee to carry on at the premises specified in the licence the business of there selling petroleum products not manufactured by him and not manufactured at those premises, and to sell them only to persons who were not licensees. It was unlawful for a licensee to sell petroleum products except as authorized by the licence held by him (s. 13 (1)). During the currency of the Act there were two "licence periods" - (a) the period commencing on 24th March 1975 and ending on 23rd September 1975, and (b) the period commencing on 24th September 1975 and ending on 23rd December 1975: s. 4 (1). The fee payable for any licence comprised a fixed sum of money and a further amount which (except in the case of a class 9 licence) was "the prescribed percentage of the value of the quantity of petroleum products sold by the applicant during the relevant period reduced by the quantity of any petroleum products non-accountable in respect of that period": s. 14 (2). The "relevant period" meant, in relation to a licence to be in force during the first licence period, the financial year ending on 30th June 1974, and in relation to a licence to be in force during the second licence period, the financial year ending on 30th June 1975: s. 4 (1). The question what quantity of any petroleum product was "non-accountable" in respect of any period was dealt with (rather obscurely) in s. 14 (1). Any petroleum product which had been sold by one licensee to another, whether or not during the relevant period (other than any of such product held for resale by the latter licensee at the end of the next preceding relevant period), and which was either resold by the latter licensee during the relevant period, or wasted or lost by the latter licensee during that period, or held for resale by the latter licensee at the end of that period, was non-accountable so far as the former licensee was concerned. This reduction for "non-accountable" petroleum product was inapplicable to the ultimate reseller who held a class 9 licence and whose fee therefore included simply "the prescribed percentage of the value of the quantity of petroleum products sold by the applicant during the relevant period". The Commissioner was given power to reassess the fee in any case where in his opinion it was assessed incorrectly: s. 22. The fee for a licence was payable when the application was made for the licence unless the applicant elected to pay the fee by instalments; in the latter case the first instalment was payable on the application: s. 19 (1) (c). However, the Commissioner might refuse to grant a licence notwithstanding that the fee was paid: s. 19 (1). The Act did not lay down any criteria to guide the Commissioner in deciding whether to grant or refuse a licence, when the application had been made in due form and the fee had been paid. Provision was made for an appeal to a tribunal against a refusal by the Commissioner to grant a licence and against the assessment or reassessment of a licence fee: s. 25.