14 permissible for a court to construe a legislative prohibition on particular conduct as creating a crime by necessary implication. [16] That issue arose in the controversial decision in R v Forlee supra, which concerned a statute that prohibited the sale of opium, save by a pharmacist under a prescription, but did not say that such a sale was a crime nor provided for a penalty for making such a sale. Mason J pointed out that the sale of opium in such circumstances had always been a crime and that the possession of opium, other than by a pharmacist or under a prescription, was said specifically to be a crime. He concluded that the absence of a penalty did not mean that the sale of opium was not an offence punishable by the courts within their ordinary powers. I agree with Greenberg JA in Zinn’s case, supra,26 that: ‘The final conclusion, in Rex v Forlee (supra), that the enactment constituted an offence was based on the broad ground that the act in question (viz., the sale of opium) was ''expressly prohibited in the public interest and with the evident intention of constituting an offence".’ The approach of the court was that an inference of an intention to criminalise the prohibited conduct could be drawn from the language of the statute even though there was no clear statement to that effect. [17] The decision in R v Forlee has been the subject of considerable academic, and some judicial, criticism on the basis that to hold that a statute creates a crime by necessary implication infringes the principle of legality.27 However, it is unnecessary to decide whether the criticism is justified, because that question does not arise in the present case. We are not asked to infer that s 5(1) and the other relevant provisions of the Act render the conduct described therein criminal. The problem in the present 26 At 355. 27 J C de Wet and H L Swanepoel, Strafreg 4 ed 46-47; C Snyman Criminal Law 5 ed 41-42; S v Francis supra at 355d-h.