The requirement of the Act that a Victorian retailer of tobacco products be licensed applies indifferently to retailers of both local and interstate products. Of itself, the requirement does not contravene s. 92 of the Constitution. If the Act imposed the ad valorem licence fee by reference to the value of all tobacco products sold by a retailer in the relevant period, the imposition of the fee would not contravene s. 92 since it would not differentiate between tobacco purchased in Victoria and tobacco purchased outside Victoria; a fortiori it would not discriminate in a protectionist sense against the purchase of tobacco outside Victoria. The exclusion of tobacco purchased in Victoria from a licensed wholesaler from the total sale value of tobacco used as the basis of the calculation of the ad valorem licence fee does, however, involve an element of differentiation and at least prima facie discrimination. Since the effect of the Act is to require all Victorian wholesalers selling tobacco products in Victoria to be licensed, the tobacco products purchased by the ordinary Victorian retailer from a local wholesaler will, for practical purposes, be all purchased from the holder of a wholesaler's licence under the Act. That being so, the exclusion of tobacco purchased in Victoria from the holder of a wholesaler's licence from the value of tobacco sold in the relevant preceding period has the effect that, for practical purposes, the licence fee paid by a Victorian retailer will ordinarily consist of the flat fee of $50 (for an indefinite licence: s. 10(1)(c)) or $10 (for a monthly licence: s. 10(1)(d)) together with an amount equal to 25 per cent of the value of any tobacco purchased from an interstate wholesaler. In other words, the retailer who sells only tobacco products purchased by him from a Victorian wholesaler will pay the appropriate flat fee for his licence, while a retailer who sells only tobacco products purchased from an interstate wholesaler will pay that flat fee plus 25 per cent of the value of tobacco sold in the preceding relevant period. It follows that, if they be viewed in isolation, the provisions of the Act imposing the obligation to pay a retail tobacconist's licence fee of $50 or $10 plus an amount calculated by reference to the value of tobacco sold which has not been purchased in Victoria from a licensed wholesaler, discriminate against interstate purchases of tobacco in favour of purchases in Victoria. If it be viewed in isolation, that discrimination is undeniably protectionist both in form and substance. In form, the provisions of s. 10(1)(c) and (d) select the fact that tobacco was "purchased in Victoria" from a licensed wholesaler as the qualifying condition for exemption from inclusion in the products by reference to which liability to ad valorem tax is calculated. In substance, those provisions protect local wholesalers and the tobacco products they sell from the competition of an out of State wholesaler whose products might be cheaper in some other Australian market place for a variety of possible reasons, e.g., that the laws of the State in which he carries on his business as a wholesaler either do not require that he hold a licence at all or exact a licence fee comparatively lower than the fee exacted from a Victorian wholesaler.