Although the subject of federally mandated institutional review boards (IRBs) has been extensively debated, we do not know much about what takes place when they convene. The story of how IRBs work today is a story about their past as well as their present, and this book melds firsthand observations of IRB meetings with the history of how rules for the treatment of human subjects were formalized in the United States in the decades after World War II. Drawing on extensive archival sources, it reconstructs the daily lives of scientists, lawyers, administrators, and research subjects working—and “warring”—on the campus of the National Institutes of Health, where they first wrote the rules for the treatment of human subjects. The author argues that the model of group deliberation which gradually crystallized during this period reflected contemporary legal and medical conceptions of what it meant to be human, what political rights human subjects deserved, and which stakeholders were best suited to decide. She then explains how the historical contingencies that shaped rules for the treatment of human subjects in the postwar era guide decision making today—within hospitals, universities, health departments, and other institutions in the United States and across the globe.