Waivers of informed consent for research participation are permitted in the United States under the Common Rule, the Health Insurance Portability and Accountability Act regulations, and the US Food and Drug Administration’s Exception from Informed Consent rule for emergency research. We assess the novel question regarding what legal right researchers have to carry out research procedures on or about another person, be it experimental medical intervention, psychological or social manipulation, or invasion of privacy, without the permission of their subjects. Our analysis frames waivers of consent as a species of presumed consent, and we address the underlying empirical question of whether it is reasonable to believe that subjects from whom no consent is sought would in fact agree, if asked. A scoping review of what is known about participation and refusal rates in United States-based research suggests that a large minority, on average, do not agree to take part in research. Refusal rates vary widely. 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. We conclude that waivers should be rare and that institutional review boards and researchers must explicitly address study acceptability in the community at large and the target population of their proposed research.