Liber Sextus, part of the Corpus Iuris Canonici, is a collection of canon law norms promulgated with the bull Sacrosanctae on March 3, 1298 by Pope Boniface VIII to integrate the "Liber Extra" with the new canonical norms issued from 1234. It was initially supposed to be an appendix to the same "Liber Extra di Gregorio IX", but it is considered a real collection as it is divided into five books, following the example already provided by the "Quinque compilationes antiquae" ( composed, in order, by Bernardo Balbi, John of Wales, Innocent IV, John the Teutonic, and Tancred of Bologna). At the end of the work appears, for the first time in a canonical compilation, the title "de regulis iuris" (in imitation of the Digest), written by the jurist Dino del Mugello. However, far from revealing knowledge of canon law, the work is substantially civil law, almost a foreign body.