Jon F. Merz, MBA, JD, PhD., is Associate Professor in the Department of Medical Ethics and Health Policy in the Perelman School of Medicine at the University of Pennsylvania. He’s taught research ethics since 1997 in the Penn Masters of Bioethics program, and he’s been the moderator of the irb forum (http://irbforum.org) since 2003. Dr. Merz is currently working on Fogarty-funded international training programs in Tanzania and Guatemala. Abstract: Waivers of informed consent for research participation are permitted under the Common Rule as well as the Exception from Informed Consent (EFIC) for emergency research rule. We examine waivers as embodiments of legal privilege, which permit actors to violate legal norms in furtherance of greater social goods. The emergency privilege, which allows a caregiver to provide emergency medical care to an incompetent victim of an accident, is the clearest example. But fundamental to the privilege to acting without consent is the presumption that reasonable persons in the patients’ position would agree, if capable, and that no evidence exists that the particular patient would not agree. An assessment of what is known about participation and refusal rates in research show that the presumption with respect to standard care is not applicable to research. This suggests that, while researchers may assert the social utility of their studies are high enough to justify waivers, there is reason to suspect that many who would be enrolled under a waiver of consent would not want to be enrolled. Our analysis suggests that waivers should be rare, IRBs and researchers must explicitly address study acceptability, and it should be incumbent upon researchers to establish by clear, sound evidence that proposed studies would be acceptable in the community at large and the target population.