The practice of cardinals electing a new pope has its origins in the tradition of the early church for a local church to elect its own bishop. St. Ambrose, for example, was chosen as bishop of Milan by the Catholics of that area, even though he was still a catechumen. He had to be baptized before he could be ordained as bishop!
Gradually the right to elect a new bishop was restricted to the priests and deacons of an area. In Rome the priests, deacons and bishops of diocese in the neighborhood of Rome were called cardinals, from the Latin word “cardo” (hinge). There still exists the distinction of cardinal bishops (of the seven dioceses surrounding Rome), cardinal priests (of the churches within Rome) and cardinal deacons (of the hospices or “stations” which provided material assistance to the poor of Rome).
In the year 1059 Pope Nicholas II gave the cardinal bishops the sole right to elect the bishop of Rome, while the other cardinals were to give assent to the election. This was a way of ensuring that the Roman Emperor and other kings would not be part of the election process and exercise undue influence.
During the Middle Ages, cardinals acquired enormous prestige within the church and were ranked above bishops, even though some of them were not even ordained as priests. In 1179 Pope Alexander III decreed that all three ranks of cardinals would participate in the election of the bishop of Rome. Pope Alexander also created the first cardinal who didn’t serve in Rome, but continued as bishop his own diocese in Germany. Previously all cardinals had to reside in Rome. Pope Alexander made this new cardinal the “titular” pastor of a church in Rome, and this tradition has continued with cardinals residing outside of Rome to this day. At one time cardinals had significant authority over their “titular” churches but today their role is one of encouragement, and in some cases of financial support.
In recent years, there have been significant changes in the college of cardinals. In 1586 Pope Sixtus V had set the maximum number of cardinals at 70, representing the 70 elders of Moses, but Pope John XXIII raised the number and Pope Paul VI set the new limit at 120. Paul VI also restricted the electors to those cardinals under the age of 80, a reform that was not greeted happily at the time by octogenarian members of the college. Pope John XXIII also required that all cardinals, whatever their rank at the time of their creation, be bishops. This requirement is sometimes dispensed with at the request of the newly created cardinal, as is the case with the American Cardinal Avery Dulles.
Perhaps the most significant change has been the internationalization of the college of cardinals. Until the time of Pope Pius XII most cardinals served as bishops of the dioceses within Italy or in the curial offices of the Vatican. Today only 17 of the 117 cardinals are Italians. This may mean that the election of an Italian pope is less likely than in past years.
Up through the election of Pope John Paul II, “two-thirds plus one” of the votes of the cardinals has been required for the election of a new pope. Pope John Paul II amended this. The new procedure requires a two-thirds vote, but if after 14 ballots no one has been elected, a vote of the absolute majority of the electors will suffice for election.
Technically, the new pope does not have to be a cardinal or a bishop to be elected. If an unordained person were elected, the dean of the college of cardinals (usually the senior cardinal bishop) would have the responsibility of ordaining the new pope. In practice, however, the newly elected pope is almost always a cardinal.