O’REGAN J and SACHS J [72] We do not agree with Ngcobo J that the stigma attaching to prostitutes arises not from the law but only from social attitudes.29 It is our view that by criminalising primarily the prostitute, the law reinforces and perpetuates sexual stereotypes which degrade the prostitute but does not equally stigmatise the client, if it does so at all. The law is thus partly constitutive of invidious social standards which are in conflict with our Constitution. The Constitution itself makes plain that the law must further the values of the Constitution. It is no answer then to a constitutional complaint to say that the constitutional problem lies not in the law but in social values, when the law serves to foster those values. The law must be conscientiously developed to foster values consistent with our Constitution. Where, although neutral on its face, its substantive effect is to undermine the values of the Constitution, it will be susceptible to constitutional challenge. [73] Moreover, we wish to make clear that our reasoning would not permit a man convicted of robbery to argue that the offence of robbery was unfairly discriminatory on the grounds of sex because more robbers are male than female, as Ngcobo J’s judgment suggests. The distinguishing characteristic of the criminal prohibition in question is that sexual intercourse for reward is intimate, shared conduct engaged in by two people, yet both are not punished by the criminal law in the same way. This does not apply to robbery or other crimes. It is the fact that the crime cannot be committed at all without the participation of another who is not rendered criminally liable in the same way by the impugned section, that gives rise to the constitutional complaint we uphold. Secondly, the crime itself is all about regulating sex and the expression of 29 See para 16 of Ngcobo J’s judgment. 44