A papal conclave is a meeting of the College of Cardinals convened to elect a new Bishop of Rome, also known as the Pope. The pope is considered by Roman Catholics to be the apostolic successor of Saint Peter and earthly head of the Roman Catholic Church. The conclave has been the procedure for choosing the pope for more than half of the time the church has been in existence, and is the oldest ongoing method for choosing the leader of an institution. A history of political interference in papal selection and consequently long vacancies between popes, culminating in the interregnum of 1268–1271, prompted Pope Gregory X to decree during the Second Council of Lyons in 1274 that the cardinal electors should be locked in seclusion cum clave (Latin for "with a key") and not permitted to leave until a new Bishop of Rome had been elected. Conclaves are now held in the Sistine Chapel of the Apostolic Palace. Since the Apostolic Age, the Bishop of Rome, like other bishops, was chosen by the consensus of the clergy and laity of the diocese. The body of electors was more precisely defined when, in 1059, the College of Cardinals was designated the sole body of electors. Since then other details of the process have developed. In 1970, Pope Paul VI limited the electors to cardinals under 80 years of age. The current procedures were established by Pope John Paul II in his apostolic constitution Universi Dominici Gregis as amended by a motu proprio of Pope Benedict XVI dated 11 June 2007. A two-thirds supermajority vote is required to elect the new pope, which also requires acceptance from the person elected.