‘Moral bioenhancement’ refers to the use of pharmaceuticals and other direct brain interventions to enhance ‘moral’ traits such as ‘empathy,’ and alter any ‘morally problematic’ dispositions, such as ‘aggression.’ This is believed to result in improved moral responses. In a recent paper, Tom Douglas considers whether medical interventions of this sort could be “provided as part of the criminal justice system’s response to the commission of crime, and for the purposes of facilitating rehabilitation : 101–122, 2014).” He suggests that they could “at least in some cases, permissibly be provided without valid consent : 101–122, 2014)” as a form of rehabilitative punishment. He argues for this conclusion by ‘parity of reasoning,’ starting from the currently accepted practice of non-consensual incarceration. His argument appears to be dependent on the successful defence of the following two claims: that non-consensual incarceration is a morally justifiable practice, and that there is no meaningful distinction between the forcible imposition of this practice, and the forcible imposition of medical interventions on prisoners. From both claims, he deduces : if non-consensual incarceration is morally justifiable, so is the non-consensual imposition of medical correctives, in some cases. In this paper, I begin by suggesting that the basic argument behind the Parity Claim results in a reductio ad absurdum, whereby any practice that is sufficiently similar to incarceration in the ways Douglas presents, would also be considered permissible. This appears to be an unpalatable conclusion, casting doubt on the soundness of a key premise. Douglas appears to offer no means of deciding which practices are sufficiently similar to incarceration in terms of harm and threat to agency, and of the practices that I will present, which do seem to be, it does not seem that he could rule them out in any principled way. Next I turn to dispute claim relating to the purported justifiability of incarceration on rehabilitative grounds. If successful, this attack causes a break in reasoning from the justifiability of incarceration, to the justifiability of medical interventions. Medical interventions would then require an alternative, independent justification, through outlining the ways in which they are conducive to a particular aim of punishment, without relying on the justifiability of incarceration. This argument has not been provided, and I suggest that attempts to do so may run into difficulty. I untangle and make explicit the various assumptions made in Douglas’ contention that medical interventions “might be thought conducive to rehabilitation in some offenders,” locating my critique in the wider debate on the causes of crime. Finally, I seek to challenge the normative weight of the Parity Claim, arguing that to show that two practices are comparable in some sense is not sufficient to show that both are equally as permissible. Other social purposes must be considered, leading me to suggest that the forcible imposition medical correctives falls beyond the appropriate remit of the criminal justice system.