The Second Council of Lyon was a pivotal assembly in the history of the Catholic Church, convened by Pope Gregory X in 1274. This gathering, taking place in the city of Lyon, France, was notable for its efforts to reform the Church's governance, specifically regarding the election of a Pope. The need for reform arose from the grievances related to the previous electoral processes, which were often marked by political maneuvering and discord among the factions within the Church. Many believed that these conflicts undermined the sanctity and authority bestowed upon the papacy.

During the council, discussions centered around creating a more standardized and equitable method for electing popes. The council ratified a significant decree that mandated the election of the Pope to occur within a specified timeframe and under specific conditions. This included the requirement of a two-thirds majority from the assembled cardinals to ensure a consensus, thus mitigating the risks associated with factionalism. The assembly brought together an impressive array of church officials from across Europe, emphasizing the unified front that the Church sought in the face of growing political pressures from various kingdoms.

In addition to regulating the papal election, the council also addressed other ecclesiastical matters, reinforcing the authority of the papacy in spiritual governance while tackling issues of heresy and moral corruption within the clergy. The decisions made in Lyon would have longstanding implications for the Catholic Church, contributing to more structured governance and the eventual evolution of the electoral process for future popes. The careful balancing of political influence and ecclesiastical authority marked a significant turning point during a tumultuous period in Church history.