Throughout this research, I describe the conceptions of law interpretation in the society around history, nevertheless unraveling the role of the judge, as well as if it is appropriate to him the use of a discretionary posture to adjust the law to a case. Thus, understanding the activity performed, and why it exists, this work splits the theories of law interpretation into two categories (positivism and post-positivism), but emphasizing, in each, twoof its main bastions and defenders - as well as their perceptions and concessions (or not) to discretionary postures. For a positivist perspective, I present Kelsen and Hart, while for a post-positivist perspective I present Dworkin and Alexy. Thereby, through these scholars, it will be established their perspectives on a possible relationship between law, principles, and morality (if there is any at all) within a legal system of interpretation of norms, and its applicability case to case. Also, I pipeline the general criticisms toward each of the two methods of interpretation of the law and how each one of these scholars perceives the role of discretion within it. So, after a theoretical and historical framework, I address the reception of positivism and post-positivism in Brazil, as well as an analysis of recent decisions portrayed by the Brazilian Supreme Court in the application of both theories. In the end, I present a possible solution- guided by Dworkin's post-positivist theory, "law as integrity"- for discretionary postures within Brazilian legal system.
