The power to punish is a tragic power, for it protects by threatening and containing violence through the use of force. Finds its legitimacy in the protection of life, integrity and freedom of people, which in the absence of legal prohibitions and a sanctioning power would be at the mercy of the law of the strongest. But inquiring, imputation, constricting and condemning, he breaks that same immunity that he keeps. Power necessary and terrible, its exercise can always degenerate into oppressive forms. We invoke the power to punish to defend our security, but how can we defend ourselves against it? Montesquieu, father of the modern separation of powers as a guarantee of the principle of legality, is revealed in this rereading of his fundamental work, From the spirit of the laws, as a criminal that teaches how citizen freedom depends on the goodness of criminal laws: the configuration of the sphere of crimes, of the composition of the arsenal of penalties, of the jurisdictional organization and of the rules of the process. The political lesson of Montesquieu inspired Cesare Beccaria, enriched the enlightened debate and contributed to the secularization, humanization and rationalization of the penal system. In him it is possible to recognize to a pioneer of the paradigm of the state of right and the constitutional democracy like system of limits to the wild powers.