Using court records involving the expert testimony of the Berlin sexologist Albert Moll, my article demonstrates that during the early 1920s a shift in the ‘epistemologies of justice’ concerning the adjudication of sex crimes took place within German courtrooms. Namely, presiding judges considered a greater number of sexual acts as punishable, despite no change in the laws themselves. Central to my argument is the role of expert testimony in practice and its critical reception. By focusing upon the rhetorical strategies presented by attorneys, judges and expert witnesses (as well as defendants themselves and their relatives), it illustrates the functions of expert and tacit knowledge in court, which were often not mutually exclusive. Moll’s stature also enabled him to translate his scientific–medical expertise into state support for his testimonies, as well as the rebuilding of an international community of sexological authorities. It was only under Moll’s leadership that the First International Sexology Congress could take place in 1926, an event that marked the apex of his prestige.
