Through a formal, rational and logical analysis of the discourse applied to penal sentences to Mapuche people, the article develops the cultural prejudices shown in courts of justice in southern Chile. The Mapuche people have made actions claiming ownership of the territory over the past twenty years, starring the political and communicational agenda in a situation that causes a permanent analytical challenge for the social sciences. By applying the analytical method it was possible to establish the manipulation of discursive expressions, assimilation of stereotypes and preconceived prejudices, and the recurrent use of discriminatory reasoning as part of practices used constantly by courts of justice. It is possible to observe. through the legal and juridical language, that not only reality is constructed and represented but also that specific forms of the power and control exercise towards minority groups of the Chilean society as it is the case of the Mapuche people are expressed.