摘要：The aim of this chapter is to determine, according to Systemic-Functional Linguistics (SFL), how the modal must is employed and which semantic contours it presents on the textual voices of the politicians participating in Public Hearings (PH). For this work to be carried out, 06 PHs on environment and sustainable development from 2012 and 2013 were selected to identify the degree of commitment of the politicians in their speeches, that is, the degree of modality. The results indicate that the manifestations in the PHs start from an implicit subjective orientation, since the politicians are the source of conviction, whilst instigating the evaluation of those present in the sessions.
关键词：Modalidade;Discurso do político;Audiências públicas
