At the heart of Robert Alexy's philosophy of law is the thesis of the double nature of law: its real dimension and its ideal dimension. While the real dimension is expressed in the elements of authoritative positivity and social effectiveness, linked with decision and coercion, the ideal dimension is defined through the correction of content and procedure that essentially includes correction Moral in the form of justice. Legal positivism associates law exclusively with its real dimension. But as soon as moral correction is added, the picture changes radically. A concept of non-positivist law arises. The thesis of the double nature therefore implies legal non-positivism. This thesis, very abstract, acquires a specific content if it develops in the direction of a complete theory of the legal system. The archimedean point of this complete theory is the thesis that the right necessarily erects a claim of correction. The essays in this book deal systematically with the various elements in which this claim is made explicit, thus constituting the best compendium of the legal philosophy of its author and a useful introduction to it.