Pope Gregory IX

Pope Gregory IX led the Catholic Church from 1227 to 1241. He strengthened papal authority, promulgated a unified canon-law collection, and authorized a papally directed inquisition against heresy.

Decretals of Gregory IX: A 1234 collection of papal rulings compiled by Raymond of Peñafort for use in canon law. This collection made papal legal decisions a more consistent authority throughout the church.
Frederick II, Holy Roman Emperor: A Hohenstaufen ruler who was Holy Roman Emperor from 1220 until his death in 1250. Their struggle over imperial power and the papal states defined much of Gregory’s pontificate.
Fourth Lateran Council: A major church council convened by Pope Innocent III in 1215 to legislate doctrine and reform. Its anti-heresy rules and reform program provided precedents Gregory pursued as pope.
Corpus Juris Canonici: The collection of authoritative canon-law texts used by the Catholic Church before its modern codifications. Gregory’s decretals became a foundational part of this enduring body of church law.
Papal Inquisition: A church tribunal system developed to investigate and judge suspected heresy under papal authority. Gregory authorized inquisitors to investigate heresy, strengthening centralized oversight of prosecutions.
Pope Innocent III: Pope from 1198 to 1216, whose pontificate greatly expanded the political influence of the papacy. Gregory, a cardinal under Innocent III, continued the drive to assert papal supremacy.
Albigensian Crusade: A military campaign from 1209 to 1229 against Cathar communities in southern France. The campaign left Gregory with an established political and religious effort to suppress Catharism.
Medieval Inquisition: A set of church procedures and institutions used in medieval Europe to investigate religious dissent. Gregory’s appointments helped establish papal direction of later inquisitorial institutions.
Canon law: The laws and legal principles governing the Catholic Church and its institutions. Gregory’s legal reforms relied on canon law to define church authority and procedure.
Saint Francis of Assisi: An Italian religious reformer who founded the Franciscan movement and died in 1226. As cardinal protector of the Franciscans, Gregory helped secure papal recognition for their movement.

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