In the contemporary world, regulating drugs, food products, consumer goods, and occupational hazards requires evidence. The basis on which such evidence should be considered reliable and valid gets to the heart of authoritative knowledge production. In mixed settings of regulatory bodies—a confluence of industrial, bureaucratic, legal, and academic work—how has this evidence been judged? Over the 20th century, regulators have relied on experts to protect consumers and workers from risky foods, drugs, consumer products, and occupational hazards. They have developed regulatory systems assuming that if frameworks and evidentiary standards are set correctly, reliable knowledge and protective practices will follow. Yet, time and again, risky products and exposures have resisted smooth bureaucratic control. Amidst a confluence of sometimes competing political, economic, and epistemic concerns, how have interested parties legitimated policy decisions? This panel addresses a set of questions related to knowledge for regulation such as: how standards have been used to try to ensure the reliability of data; what regulators have done when evidence was inadequate or inconclusive; how competing value systems have been negotiated; and what has happened when risks did not conform to existing classifications. The papers examine international efforts to regulate toxicological laboratory practice, fetal protection policies in the U.S. industrial workplace, and U.S. Food and Drug Administration food and drug labeling practices. The session aims to generate discussion about how risk and responsibility have been formed and reformed, what has counted as evidence, and the sometimes surprising ways power has been instantiated in bureaucratic settings.