Drawing on case studies from the modern era of pharmaceutical regulation in the UK, US and Europe, I examine how the extent and distribution of trust between regulators, the pharmaceutical industry, and the medical profession about drug testing and monitoring influences knowledge and regulatory judgements about the efficacy and safety of prescription drugs. Introducing the concepts of ‘acquiescent’ and ‘investigative’ norms of regulatory trust, I demonstrate how investigative norms of regulatory trust—which deter pharmaceutical companies from assuming that their data analyses (...) will be accepted without independent de-construction—drive up bioethical and regulatory standards of drug assessment in the interests of health. By contrast, acquiescent norms of regulatory trust, which are associated with industrial capture and professional closure of interests, promote permissive standards allowing patients to take pharmaceuticals with greater risks to health and less evidence of therapeutic efficacy. (shrink)