The concept of vulnerability has been the topic of considerable discussion in research bioethics, largely because of dissatisfaction with early constructions of the concept that were based on subpopulations of research subjects. These subpopulations have attributes likely to undermine their capacity to provide autonomous informed consent: persons who are relatively or absolutely incapable of protecting their own interests through negotiations for informed consent. Several subpopulations were seen as requiring special protections, including children, pregnant women, prisoners, racial minorities, the economically disadvantaged, (...) the very sick, and the institutionalized. Recent years have witnessed the identification of other subpopulations with attributes that could render them vulnerable, as well. For example, the Council for the International Organization of Medical Societies has named such potentially vulnerable groups as the homeless, nursing home residents, patients with incurable diseases, patients in the emergency department, employees, students, and members of communities who are unfamiliar with modern medicine. (shrink)