The article is devoted to the structural features of the headlines in the legal text of the 18th century in connection with their functions. Source of the study was the Draft Charter on Prisons (1787), composed by Catherine II with the aim of detailed provisions of a new device of the prisons in Russia. The relevance of the work lies in the need to study the role of the headline in the text of the document in order to better represent the process of formation of this genre. The novelty of the study is due to the fact that the prescriptive function of the title of the legal text is considered to be dominant in some cases. The author dwells on the specifics of the Draft of 1787 in comparison with other penitentiary documents of the 18th-19th centuries. Attention is drawn to the multifunctional nature of the title of legal text and the dominant role of one or another of its functions. Particular attention is paid to the forms of the title depending on the degree of expression of the function in a certain paragraph of the document. The classification of headlines in the legal text depending on the dominant role of a particular function of the headline is proposed. The author gives examples of contamination of informative and prescriptive functions of headlines with indication of cases of such mixing. It is noted that this kind of research complements the picture of the formation of the official business style.