Because we can: clashes of perspective over researcher obligation in the failed PrEP trials.

This article examines the relationship between bioethics and the therapeutic standards in HIV prevention research in the developing world, focusing on the closure of the pre-exposure prophylaxis (PrEP) trials in the early 2000s. I situate the PrEP trials in the historical context of the vertical transmission debates of the 1990s, where there was protracted debate over the use of placebos despite the existence of a proven intervention. I then discuss the dramatic improvement in the clinical management of HIV and the treatment access movement, and consider how these contexts have influenced research practice. I argue that as HIV prevention trials oblige researchers to observe the rate at which vulnerable people under their care acquire HIV, there is an obligation to provide antiretroviral treatment to seroconverters and other health care benefits that fall within the scope of researchers' entrustment, both to avoid exploitation and to enact reciprocal justice. I argue against propositions that the obligations to provide specific benefits are vague, fall only upon researchers and sponsors, and create injustices by privileging the few over the many. Finally, I contend that the realisation of a broader standard of care in HIV prevention research broadens the role of research from being a simple tool to produce knowledge to a complex intervention that can play a part in the reduction of health disparities.