On several occasions in its two millennia-history, the Catholic Church has changed the rules for choosing a new Pope. The Bible itself offers no specific guidelines on pontifical succession. The current method is based on the texts and edicts of the following Popes.
- In 1060, Pope Nicolas II published the Papal bull (or charter) In nomine Domini, which designated cardinal-bishops as the sole electors of the Pope. Prior to this, Pontiffs had been chosen by various prominent non-members of the Church and prominent figures such as Roman emperors or out-going Popes themselves.
- Pope Gregory X promulgated another Papal bull, Ubi Periculum, which fixed the rules of the conclave, including the sequestration of the cardinals and prohibition of communication with the outside world.
- In November 1970 Pope Paul VI established further rules of the electoral college: the conclave could include a maximum of 120 cardinals, each of whom must have a maximum age of 80.
On the evening of February 28, 2013, when Benedict XVI officially stepped down the period of "Sede Vacante" or 'Vacant Seat' started, that is to say, the vacancy of the Holy See. This year, 115 cardinals will take part in the election, all of them under 80 years old, as required by Catholic law.
The election of the future Pontiff takes place within the walls of the Sistine Chapel. During the election, the cardinals are locked inside. In practice, the Cardinals will elect a Pope amongst themselves, though it is theoretically possible to elect any adult Catholic male.
A candidate must obtain a two-thirds majority in the vote to be elected. Different ballots are held for a conclusive result. If after three days there is no winner there are three more phases of seven votes and after this all but the two leading candidates will be "eliminated" and the vote then falls between only the top two. After each round, the ballots are then burned in the chapel fireplace. If the future pope is not decided in this vote then black smoke from the chimney will inform the outside world of its failure.
If the necessary majority is reached, the dean of cardinals addresses the one who has obtained the necessary votes and asks him the following question: "Do you accept your canonical election as Supreme Pontiff?". If he accepts, the Dean then asks, "By what name do you want to be called?". The world is then informed of the appointment of a new Pope by white smoke from the chimney and the bells of St. Peter.
From the central balcony of St. Peter's Basilica, Cardinal Protodeacon declares "Habemus papam" (We have a Pope). The identity and the reign name chosen by the new Pope is then revealed and a new Pontificate begins.