Abstract : The Institutiones iuris canonici of Giovan Paolo Lancellotti (1522-1590), a handbook of canon law, was published in 1563, and has been regularly edited until the end of the 18th century, in a monographic form or joined to the Corpus iuris canonici. This book affiliated to legal humanism (or mos gallicus), announces a rupture in canonical science. It adopts the tripartite plan " personæ-res-actiones " of the Justinian's Institutes ; aims to expose the whole of the Latin Church law by excluding civil law ; and is organized in books, titles and concise paragraphs. It breaks with the Medieval tradition which practiced dialectic methodology, and inserts the Catholic Church into the great codification movement. Lancellotti's book is presented in the context of its emergence (intentio auctoris), is submitted to external and internal criticism (intentio operis), and is analysed in the context of its reception up until the institution of modern canon law (intentio lectoris).