1917 Code of Canon Law  The 1917 Code of Canon Law, also referred to as the Pio-Benedictine Code, was the first official comprehensive codification of Latin canon law. It was promulgated on 27 May 1917 and took legal effect on 19 May 1918. It was in force until the 1983 Code of Canon Law took legal effect and abrogated it on 27 November 1983. It has been described as "the greatest revolution in canon law since the time of Gratian" (1150s AD). Papal attempts at codification of the scattered mass of canon law spanned the eight centuries since Gratian produced his "Decretum" c. 1150. In the 13th century especially canon law became the object of scientific study, and different compilations were made by the Roman Pontiffs. The most important of these were the five books of the "Decretales Gregorii IX" and the "Liber Sextus" of Boniface VIII. The legislation grew with time. Some of it became obsolete, and contradictions crept in so that it became difficult in recent times to discover what was of obligation and where to find the law on a particular question. Since the close of the ‘’Corpus Juris’’ numerous new laws and decrees had been issued by popes, councils, and Roman Congregations. No complete collection of them had ever been published and they remained scattered through the ponderous volumes of the ‘’Bullaria’’ the ‘’Acta Sanctae Sedis’’, and other such compilations, which were accessible to only a few and for professional canonists themselves and formed an unwieldy mass of legal material. Moreover, not a few ordinances, whether included in the ‘’Corpus Juris’’ or of more recent date, appeared to be contradictory; some had been formally abrogated, others had become obsolete by long disuse; others, again, had ceased to be useful or applicable in the present condition of society. Great confusion was thus engendered and correct knowledge of the law rendered very difficult even for those who had to enforce it. Already in the Council of Trent the wish had been expressed in the name of the King of Portugal that a commission of learned theologians be appointed to make a thorough study of the canonical constitutions binding under pain of mortal sin, define their exact meaning, see whether their obligation should not be restricted in certain cases, and clearly determine how far they were to be maintained and observed.