canonization (kănˌənĭzāˈshən) [key], in the Roman Catholic Church, process by which a person is classified as a saint. It is now performed at Rome alone, although in the Middle Ages and earlier bishops elsewhere used to canonize. Beatification, by which a person is called blessed and his or her cult is approved, requires proof of a miracle through the candidate's intercession (unless the candidate for sainthood was martyred) and proof that the candidate's life was exemplary, and must precede canonization. A candidate for sainthood may be declared venerable before beatification if the person led an exemplary life. Canonization requires proof of at least one additional miracle (occurring after beatification) attributable to the saint.
Until 1983 the process of canonization was like a trial at which the saint was said to be defended by the church; a prosecutor was appointed to attack all evidence alleged in favor of canonization. The prosecutor was popularly called advocatus diaboli [devil's advocate], his opponent the advocatus Dei [God's advocate]. The process has now been streamlined, and the position of devil's advocate eliminated.
The first solemn canonization seems to have been that of St. Ulrich late in the 10th cent. The method of formal canonization was set by the enactments of Urban VIII that came into force in 1634. In the Orthodox Eastern Church, a synod of bishops within a self-governing church has the authority to canonize.