Papal bull
This article is about the bull regulating papal conclaves. For other uses, see Aeterni Patris (disambiguation).
Aeterni Patris Filius (English: Son of the Eternal Father), also called Aeterni Patris, was a bull issued by Pope Gregory XV on 15 November 1621 that regulated papal conclaves. Together with the bull Decet Romanum pontificem of 1622, it formed the canonical basis for papal elections until the 20th century. The bull brought about many reforms to the papal election system, created structured rules, and sought to decrease the influence of organized factions within the College of Cardinals during the conclave as well as decrease the influence of secular monarchs on papal elections. It established general rules for the conclave process, while the later bull Decet Romanum pontificem addressed the ceremonial aspects of papal elections.