On the impartiality of early British clinical trials

•An account of the adoption of clinical trials as a regulatory standard for drug testing.•I vindicate the actual role of impartiality as non-manipulation in the acceptance of trials.•An alternative approach to the history of the social uses of statistics.

Did the impartiality of clinical trials play any role in their acceptance as regulatory standards for the safety and efficacy of drugs? According to the standard account of early British trials in the 1930s and 1940s, their impartiality was just rhetorical: the public demanded fair tests and statistical devices such as randomization created an appearance of neutrality. In fact, the design of the experiment was difficult to understand and the British authorities took advantage of it to promote their own particular interests. I claim that this account is based on a poorly defined concept of experimental fairness (derived from T. Porter’s ideas). I present an alternative approach in which a test would be impartial if it incorporates warrants of non-manipulability. With this concept, I reconstruct the history of British trials showing that they were indeed fair and this fairness played a role in their acceptance as regulatory yardsticks.