Using 350 « lettres de provisions de charge » related to the magistrates of the parlement of Bordeaux, in charge between 1643 and 1715, this article aims at showing that this document, usually considered as a common and poor source, is essential to lead a statistical study of the careers, an approach that was renewed, due to the use of informatics in historical researches. Moreover, this source can be used for more atypical studies, if we consider what is out of the ordinary.