Very few documents enable the historian to understand Robespierre as a lawyer in his work. His professional correspondence, his legal queries, his consultations, his legal defense and other acts of his profession have virtually all disappeared, except for his factums of which nearly all have survived. This last exceptional corpus of twelve printed documents enables us to investigate a facet of his activity as a lawyer, that of the author of factums, which constitute in themselves a veritable legal genre. By studying these documents, it is possible to analyze the techniques Robespierre used to promote a particular case or cause, and to persuade the two chief recipients of his writings : the judges and the public. What language did he use ? How did he convince them ? How did he garantee his client a favorable judgement as well as public estime ? The answer depends not only on the development of arguments legal and factual, but also on the way in which these arguments are developed. The narrative strategies, the use of pathos, the possible choice of a rupture defense that challenged the legitimacy of « inferior » judges and the relevancy of a given law, reinforced by a lawyer’s ethos of the «unfortunate» gives to the writings of Robespierre their particular force.