Pre-exposure prophylaxis (PrEP) (Truvada) is a medication which if taken correctly is almost entirely effective in preventing HIV infection. In regions and countries where it has been widely taken up, HIV seroconversion rates have significantly decreased. Alongside testing and treatment, it offers the very real prospect of ending HIV infections. However, in England, commissioning it has (and still is) a controversial process, where NHS England has repeatedly raised supposed ‘uncertainties’, first legal and then scientific. The same has not happened in Scotland, where PrEP was commissioned to anyone who needed it in April 2017. This article presents a close reading of the IMPACT trial protocol, which we conclude cannot answer the questions it sets out to answer. We then suggest that the uncertainties the trial claims to address are in fact a tool of power which is deployed to strategically ration healthcare; introduce uncertainty about commissioning PrEP; and shift the boundary between individual responsibilities and state responsibilities for public health and HIV prevention. We conclude that all the above constitute an unethical use of clinical trial rhetoric, systematically discriminate against minority and vulnerable groups, and ration healthcare for those who most need it. As such, we call on all academics, clinicians and activists to resist further unethical misuses of clinical trial rhetoric.