How does the public view the offer of a biological treatment in lieu of prison for criminal offenders? Using the contrastive vignette technique, we explored this issue, using mixed-methods analysis to measure concerns regarding changing the criminal's personality, the coercive nature of the offer, and the safety of the proposed treatment. Overall, we found that of the three variables, the safety of the pill had the strongest effect on public acceptance of a biological intervention. Indeed, it was notable that the public was relatively sanguine about coercive offers of biological agents, as well as changing the personality of criminals. While respondents did not fully endorse such coercive offers, neither were they outraged by the use of biological treatments of criminals in lieu of incarceration. These results are discussed in the context of the retributive and rehabilitative sentiments of the public, and legal jurisprudence in the arena of human rights law.