Normativity has Always been taken as something mysterious. Many explanations from a range of different areas were given about this phenomenon, though, no definitive one. Legal normativity is no different. Aiming to bring new lights to this cloudy subject, the starting point of the present investigation is Hebert L. A. Hart s concept of internal legal statements. Through a sociolinguistic analysis, the author claims that such statements committed with the law are to be seen as expressions of rule s acceptance. Nevertheless, Hart does not go further and a lot of relevant points and questions arise both about the best way to read his work and on the real explanatory power of his theory. There are evidences in his writings that allow us to read his theory in a very similar way to Allan Gibbard s metaethics one. This line of though seems to be a sophisticated version of a non-cognitivism and, therefore, sees normative terms as used to express conative states of mind. These mental states are different from a belief and hence cannot have truth aptness. We intend to show that such theoretical posture, expressivist, is very alluring for the legal philosopher, since it can explain the internal legal claims and its implicit relationship with normativity. Further, this perspective is capable of answering critics posed by cognitivists about Hart s conceptual work. By means of an analysis of how expressivism can answer traditional metaethical questions, it is possible to make the legal expressivist position even more solid, and to switch the argumentative burden to opponent side of the dispute. Lastly, we will indicate an interpretation of a social and psychological background mechanism to norm expressivism. The recent body of scientific evidence provides a license for optimism in favor of expressism s ability to unveil the mystery of normativity.