The present work aims to analyze the problem of the structural selectivity of the Brazilian penal system, as an instrument of social control, since the principle of isonomy does not seem to be applied, going against with the offi cial discourse that tends to present Criminal Law with an isonomic feature, equally punishing all those who violate incriminating precepts to become selective, repressive, stigmatizing and with strong hygienist traits for a certain social layer. This article seeks to unravel this selectivity in its modus operandi, by trying to understand the selective functioning of the modern Brazilian penal system, highlighting the points in which the repressive state system, analyzing current examples of the diff erentiation of State action in the lower social classes to the detriment of the higher levels and, when functioning in this way, it proves to be ineffi cient in several points of view.