This paper investigates the role of ratio decidendi in the construction of the súmula vinculante n. 33, issued
by the Brazilian Supreme Court. For this, I analyzed the cases listed as “repeated cases on constitutional matters” (a requirement for approving a súmula, which is a binding precedent in Brazilian law) and the
rulings cited in these cases. I also analyzed the proposal of the súmula vinculante n. 33 and its related debates. My objective was to investigate whether the Court had met the requirement of “repeated cases on constitutional matters”. As a result, I concluded that the súmula vinculante n. 33 did not meet this requirement, although the Justices were concerned about it.