This work deals with an approach of The metaphysics of customs in which the idea of Kant’s Categorical Imperative is questioned, starting from the Lacanian principles of pleasure and reality treated in the book 7, The seminar: the ethics of psychoanalysis. The objective will be to analyze the categorical imperative as the basis of internal owe-being of the moral and juridical conduct, questioning the validity of this autoconscientious imperativity of action in the context of ethical evaluations of individual's purpose.With this study one searches to demonstrate, primordially from the psychoanalytical point of view, the necessity of a conscience superstructure or a ‘superego’, so that the individual can construct his intentionality within the limits of the regulating precept of conduct, what would be impossible of being structured in psyche according to Kant’s proposal: the impossibility of this construction points to the categorical imperative invalidation as foundation of the internal owe-being. In the face of Kant’s own argument silence, it will be sought to identify what makes possible, internally to the individual, the practice of ethical action as if it were a possible natural movement which corresponds to its fundamental practical intentions, and not only to the external owe-being. This identification becomes possible starting from the principle of pleasure and reality as they are approached by Lacan in his ethics of psychoanalysis