Ethics has been identified as a central reason for choosing a stepped wedge trial over other kinds of clinical trials. The stepped wedge design uses phased implementation, which means that all arms of the trial receive the active intervention over the course of the study. Some groups receive it later than others, but the intervention is not withheld from any group. This system of phased implementation has been identified as ethically advantageous in two instances: (1) when the intervention is thought to be especially likely to be effective and (2) in emergency situations, such as research conducted during emerging epidemics. But despite the increased use of the stepped wedge design and appeals to its ethical superiority as the motivation for its use, there has been little attention to the stepped wedge in the ethics literature.

In this talk I will consider whether there are persuasive reasons to prefer or to require a stepped wedge trial. I will argue that while the stepped wedge is ethically permissible, it is not morally superior to other kinds of trials. To this end, I will examine the ethical justification for providing, withholding, and delaying interventions in research.