This paper explores how a particular form of regulation—prior ethical review of research—developed over time in a specific context, testing the claims of standard explanations for such change (which center on the role of exogenous shocks in the form of research scandals) against more recent theoretical approaches to institutional changes, which emphasize the role of gradual change. To makes its case, this paper draws on archival and interview material focusing on the research ethics review system in the UK National Health Service. Key insights center on the minimal role scandals play in shaping changes in this regulatory setting and how these depend upon the absence of a single coherent profession (and accompanying social contract) associated with biomedical research.