Decretals (Epistolae decretales) is the name that's given in Canon law to those letters of the pope which formulate decisions in ecclesiastical law. They are generally given in answer to consultations, but are sometimes due to the initiative of the popes. These furnish, with the canons of the councils, the chief source of the legislation of the church, and formed the greater part of the Corpus Iuris Canonici before they were formally replaced by the Codex Iuris Canonici of 1917. However, Cardina… (More on Decretal)