Here's how a conclave elects a new pope
Secretive, centuries-old process once took years
As Pope Francis continues to battle double pneumonia in hospital, his poor health is casting a spotlight on the arcane process of how the Catholic Church elects its leader.
The papal "conclave" is intentionally shrouded in mystery — the term itself is Latin for "locked room" — but here are some of its rules and wrinkles:
Who is eligible?
Candidates must be male and a baptized Catholic. And, though it is not an explicit requirement, nearly every pontiff has been a cardinal before they were elected.
Who votes?
The pope is chosen by 120 cardinals who must be under the age of 80 at the time of the previous pope's death or resignation.
As of Jan. 22, the world has 252 cardinals, of which 138 fit the age requirement. It's not clear how the 120 are chosen. Those over the age of 80 can participate in preliminary meetings.
What is the process?
The conclave's first day begins with the special mass, after which the cardinals file into the Sistine Chapel chanting prayers and hymns, imploring saints and the Holy Spirit to help them pick a pope. Each cardinal places his hand on a book of the Gospels and pledges "with the greatest fidelity" never to reveal the details of the conclave.
The master of the papal liturgical celebrations, an official who organizes religious ceremonies by the pontiff during his tenure, then cries "Extra omnes" — Latin for "All out." Everyone except the cardinals leaves and the voting can begin.
There is extreme secrecy to the process. According to the archdiocese of Toronto, cardinals can be excommunicated if they leak information and the chapel is swept for listening devices before and after the conclave.
How do they vote?
Each cardinal writes his choice on a paper inscribed with the Latin words for "I elect as supreme pontiff." They approach the altar one by one and say: "I call as my witness, Christ the Lord who will be my judge, that my vote is given to the one who, before God, I think should be elected."
The folded ballot is placed on a round plate and slid into an oval silver-gold urn. Once cast, the ballots are opened one by one by three scrutineers, who note the names down and read them aloud.
Cardinals can keep their own tally on a sheet of paper provided but must turn their notes in to be burned at the end of voting.
The scrutineers then add up the votes and write the results on a separate sheet of paper which is preserved in the papal archives.
As the scrutineer reads out each name, he pierces each ballot with a needle through the word "eligo" (Latin for "I choose"), binds the ballots with thread and ties a knot.
The ballots are then put aside and burned in the chapel stove along with a chemical to produce either white or black smoke; white when a round of voting leads to a new pope and black when it does not.
How long does a conclave last?
Only one ballot is held on the first day, with up to four rounds of voting allowed each day after that. A two-thirds majority is needed to win.
If no one is elected after three days, voting pauses for up to one day. Voting resumes and if no pope is elected after another seven ballots, there is another pause, and so on until about 12 days of balloting have passed.
If no one is selected after 33 rounds, the cardinals go to a runoff of the top two contenders, under a relatively new rule introduced by Pope Benedict XVI. Unlike in previous rounds, those two candidates cannot cast ballots.
Conclaves used to last for months, the longest on record being for the selection of Gregory X in the 13th century, which lasted from November 1268 until September 1271 due to infighting and outside meddling.
To prevent the same chaos that saw him elected, Gregory X enacted new rules that sequestered the electors and locked them in — hence the term "conclave."
Despite some outliers, such as the conclave of 1740 that lasted from February to August, the process now tends to take just days or sometimes weeks. The average conclave in the 20th century was just three days, and the two so far of the 21st century, for Francis and Benedict, took just five and four ballots, respectively.
What happens once a pope is elected?
Once a pope is elected, the master of the papal liturgical celebrations returns to the chapel and the dean of the College of Cardinals — who runs the conclave if they under 80 years old — asks the winner: "Do you accept your canonical election as supreme pontiff?"
Assuming the cardinal says "I accept," the dean asks: "By what name do you wish to be called?"
Papal names were originally meant to Catholicize the winner's birth name. Pope John II, elected in 533, was the first to do this because he was born Mercurius, after the Roman god Mercury. They are now often taken as an homage to previous popes, and as an indication of the new one's approach to the job.
The master of liturgical ceremonies then enters the information on a formal document, white smoke pours out of the Sistine Chapel chimney and the bells of St. Peters Basilica toll.
The new pope then changes into his white cassock, and one by one the red-clad cardinals approach to swear their obedience.
The new pope will stop and pray in the Pauline Chapel for a few minutes before emerging on the loggia of the balcony overlooking St. Peter's Square. Preceding him to the balcony is a cardinal who announces "Habemus papam!" ("We have a pope!") and then introduces him to the world in Latin.
The new pontiff then emerges and delivers his first public words as pope.
With files from CBC News and Reuters