In this article we analyze interactions involving interpreters in a preliminary hearing tribunal in Denmark. We use an interactional sociolinguistic approach to focus on a recurrent sequence of events in which certain information is not explicitly mentioned by the prosecuting authorities, probably because it can be inferred by institutional actors, although not by the accused. Interpreters make semantic modifications to the wording of the prosecutor in their translations in order to help the accused understand. We believe that the interpreters make use of pragmatic communication competencies and of their own suppositions regarding the knowledge of those addressed in such circumstances, adding information about the judicial system and its procedures. We discuss the way in which the institutional framework restricts the range of interactions available to participants, in particular the opportunity for the interpreter to check that the accused has understood.