This short article analyzes the progressive constitution of Jean Piaget's book Le jugement moral chez l'enfant (1932) and the political reading that this work allowed. The Institut Rousseau, where Piaget had worked since 1921, was far from being a virgin territory: several studies on the question of moral judgment had already been published, in particular by Pierre Bovet. As early as 1926, however, Piaget set up a research program that was based on the ideas in vogue at the Institute, but which also went beyond them. Bovet's theory of respect was thus dialecticized by the discovery of two types of respect: unilateral and mutual. By exploring concepts of law, sociology and morality in order to unify them in his socio-psychological theory of the two respects, Piaget extended its scope to the point of transforming it into a tool for a political reading of the events of the 1930s, in particular the rise of fascism.