In this paper, the author proposes an analysis of the apparently contradictory attitudes towards transactional sexual exchanges, as they have emerged in public debate and informed legislation and policies in Italy over the past few years. The ambiguity towards commercial sex is linked to a specific dynamic of power, which denies sexual labour the status of work and makes it the object of repressive and criminalising policies, whilst at the same time habitually demanding sexual services in exchange for money, gifts or favours. The article shows how criminalisation functions as a prominent form for the control of subjects, related to the workings of sovereignty. In particular, the author considers the ways in which the criminalisation of prostitution and of undocumented migration, which compound in the figure of the migrant prostitute, represents a means for the exertion of sovereignty and relates to the centrality of desire, transgression and their disciplining in the contemporary context. However, closer examination of the subjective experiences of those who are supposedly excluded and criminalised, such as undocumented migrant sex workers in detention centres, reveals the incompleteness of disciplinary mechanisms.