idea of scheduling the conclave to include or exclude a cardinal who is very close to the age limit (and in 2013, Cardinal Walter Kasper, 79 when the papacy became vacant, participated in the conclave at age 80). Choice of electors and of candidates Originally, lay status did not bar election to the See of Rome. Bishops of dioceses were sometimes elected while still catechumens, such as the case of St. Ambrose, who became Bishop of Milan in 374. In the wake of the violent dispute over the 767 election of Antipope Constantine II, Pope Stephen III held the synod of 769, which decreed that only a cardinal priest or cardinal deacon could be elected, specifically excluding those that are already bishops. Church practice deviated from this rule as early as 817 and fully ignored it from 882 with the election of Pope Marinus I, the Bishop of Caere. Nicholas II, in the synod of 1059, formally codified existing practice by decreeing that preference was to be given to the clergy of Rome, but leaving the cardinal bishops free to select a cleric from elsewhere if they so decided. The Council of 1179 rescinded these restrictions on eligibility. On 15 February 1559, Paul IV issued the papal bull Cum ex apostolatus officio, a codification of the ancient Catholic law that only Catholics can be elected Popes, to the exclusion of non-Catholics, including former Catholics who have become public and manifest heretics. Pope Urban VI in 1378 became the last pope elected from outside the College of Cardinals. The last person elected as pope who was not already an ordained priest or deacon was the cardinal-deacon Giovanni di Lorenzo de' Medici, elected as Pope Leo X in 1513. His successor, Pope Adrian VI, was the last to be elected (1522) in absentia. Archbishop Giovanni Montini of Milan received several votes in the 1958 conclave though not yet a cardinal. As the Catholic Church holds that women cannot be validly ordained, women are not eligible for the papacy. Though the pope is the Bishop of Rome, he need not be of Italian background. , the three most recent conclaves have elected a Pole (1978), a German (2005), and an Argentinian (2013). A simple majority vote sufficed until 1179, when the Third Council of the Lateran increased the required majority to two-thirds. As cardinals were not allowed to vote for themselves (after 1621),