This article examines, through statistical methods, the effects of judges’ and defendants’ gender on sentencing decisions by the São Paulo Court of Justice. The research analyzed first-instance criminal convictions handed down in 2022 for four high-incidence offenses — simple theft, qualified theft, robbery, and drug trafficking — using non-parametric tests and a multiple linear regression model. The results show that, in drug trafficking cases, male judges impose significantly harsher sentences than female judges, even when controlling for relevant legal variables, while the defendant’s gender does not present statistically significant effects. The study engages with the international literature on quantitative sentencing research and contributes to the advancement of empirical legal studies in Brazil by applying rigorous methods to the analysis of sentencing decisions. Finally, the findings raise relevant hypotheses regarding the influence of gender on judicial reasoning and on the formation of a punitive institutional ethos within the Brazilian judiciary.