The Decretum Gratiani or Concordia discordantium canonum (in some manuscripts Concordantia discordantium canonum) is a collection of
Canon law compiled and written in the twelfth century as a legal textbook by a jurist (perhaps) named
Gratian. It forms the first part of the collection of six legal texts, which became known as the
Corpus Juris Canonici and which retained legal force in the
Roman Catholic Church up until Pentecost Sunday, May 27, 1917, when the a revised Code of Canon Law (Codex Juris canonici) was promulgated by Pope Benedict XV. (The Code became binding throughout the Western Church the Pentecost Sunday of the following year, 19 May 1918.)
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