Abstract
This paper focuses on the role of regulation in the shaping new scientific facts. Fleck chose to study the origins of a diagnostic test for a disease seen as a major public health problem, that is, a ‘scientific fact’ that had a direct and immediate influence outside the closed universe of fundamental scientific research. In 1935, when Fleck wrote his book, Genesis and development of a scientific fact, he believed that the tumultuous early history of the Wassermann reaction had come to an end, and that this reaction was successfully stabilized through the standardization of laboratory practices and thanks to the rise of a specific professional segment—the serologists. He could not have predicted that in the 15 years that followed the publication of his book, regulatory measures—barely metioned in his historical narrative—would play a key role in the destabilization of the original meaning of this reaction. The introduction of mass screening for syphilis—mainly via legislation that introduced obligatory premarital tests and promoted the testing of pregnant women—weakened in fine the link between Wassermann serology and infection by the etiological agent of syphilis, the bacterium Treponema pallidum. Fleck elected to study the Wassermann reaction because of its novelty, its complexity, and because it became the focus of a controversy regarding its origins. However, the Wassermann reaction was also one the first examples of a medical technology regulated by the state and incorporated into legal dispositions. It may therefore be seen as an exemplary case of the close intertwining of scientific investigations, their practical applications and regulatory practices.