The aim of the third chapter is to reconstruct Ralf Dreier's and Robert Alexy's argumentations in favour of the nonpositivist concept of law. The structures of their argumentation are also presented in schematic form. After having discussed the methodological framework of the nonpositivist argumentation, we provide a description of Dreier's nonpositivist argumentation in which the fundamental role is played by two classic arguments against the positivist understanding of law: the argument from injustice (Unrechtsargument) and the argument from principles (Prinzipienargument). Alexy's argumentation in favour of the necessary conceptual relation between law and morality and the nonpositivist understanding of law is presented in two stages. At first, the subject of the discussion is the original version of Alexy's nonpositivist analytical and normative argumentation, also based on the Unrechtsargument and the theory of principles, as well as on the argument from correctness introduced by him. Then, the subject of the reconstruction is the ultimate form of his nonpositivist argumentation, taking into account the modifications and additions proposed by Alexy in the monograph Begriff und Geltung des Rechts of 1992.