Members of the College of Cardinals who are under the age of 80 are eligible to vote for the Pope.

A cardinal may be retired from his last post, but if he is still under 80, he may vote in the election.

There is a short interval of time between the date the Chair of Peter becomes vacant (sede vacante) and the date on which the conclave begins. Any cardinal who is under the age of 80 at the time of sede vacante may vote, even if he turns 80 before the actual conclave. For example, Cardinal Kasper of Germany turns 80 on March 5, but since he was still 79 at the time of Benedict XVI’s resignation, he is eligible to vote for the new pope.

As of this writing, there are two of the 117 age-eligible cardinals who will not be voting:  Cardinal Julius Riyadi Darmaatmadja of Indonesia is excused due to his poor health, and Cardinal Keith O’Brien of Scotland resigned February 25 and announced that he would not attend the conclave. This leaves 115 cardinals to elect the new Pope.

A chart listing all age-eligible cardinals can be found at canonlaw.info.

The cardinals’ votes are counted by three cardinals (the “scrutineers”) who are chosen for the job at random. In addition, three other randomly-chosen cardinals (the “revisers”) verify the ballot count. All of the ballot counters are selected during the conclave itself, before the task of electing the pope begins.

Retired Cardinal Edmund Szoka of Detroit describes the process:

There is no “politicking,” Cardinal Szoka emphasized — no campaigning, no nomination speeches, not even a simple placing of names in nomination. Each cardinal simply writes a name on a ballot and presents his ballot.

“When we take the ballot up to the altar, we have to repeat our oath that we have voted for the one best suited,” Cardinal Szoka said.

The new urns into which votes will be placed, the left-most replacing the oversized chalice.

At the altar, the ballot is placed “on a flat disk, like a paten, and then — without touching the ballot — it is tipped into a chalice, and is then collected from the chalice and counted.”

After the ballots are counted, and that initial tally is verified, the results are announced to the conclave, but never to anyone else; no records are kept, and the ballots are burned by a couple of masters of ceremony who are the only non-cardinals in the chapel.

To finish the balloting and select a Pope, one candidate must have received over two-thirds of the votes of the Cardinals participating in the Conclave.

Cardinals are not permitted to communicate with anyone outside the election area during a papal conclave. They may not

• use social media
• make phone calls
• mail or receive letters
• watch television
• listen to the radio
• read newspapers
• make video, tape or electronic recordings of the conclave

The conclave takes place in the Sistine Chapel, which will be inspected for hidden cameras and other recording devices before the conclave begins. Any notes that are taken by the Cardinals during the conclave will be burned along with the ballots.

In 1996, Blessed Pope John Paul II issued a document, Universi Dominici Gregis, that established new rules for the conclave. It emphasized “the duty of maintaining the strictest secrecy with regard to everything that directly or indirectly concerns the election process itself.”

Each Cardinal will make the following pledge:

We, the Cardinals of Holy Roman Church, of the Order of Bishops, of Priests and of Deacons, promise, pledge and swear, as a body and individually, to observe exactly and faithfully all the norms contained in the Apostolic Constitution Universi Dominici Gregis of the Supreme Pontiff John Paul II, and to maintain rigorous secrecy with regard to all matters in any way related to the election of the Roman Pontiff or those which, by their very nature, during the vacancy of the Apostolic See, call for the same secrecy.

Next, each Cardinal shall add: And I, N. Cardinal N., so promise, pledge and swear. And, placing his hand on the Gospels, he will add: So help me God and these Holy Gospels which I now touch with my hand.

Chapter II, Article 44 of Universi Dominici Gregis explains that the Cardinal electors may not communicate “by writing, telephone or any other means of communication” with anyone outside the election area unless there is proven and urgent necessity, until the election is concluded and a public announcement of the result has been made.

The conclave lasts until a new Pope is elected.

According to the rules for a conclave established by Pope John Paul II in 1996, the only form of election that may take place is the Scrutiny, or ballot.

That does not mean that there will only be one ballot. In a papal election, there must be a majority. The winner does not simply get one more vote than his nearest competitor.

Until Pope Benedict XVI’s Motu proprio of June 11, 2007, the rules for “majority” could change during the course of a conclave.

Under this new rule, a two-thirds majority is required for the election of a new pope, no matter how long it takes. If, after three days of voting, a new Pope is not elected, one day would be dedicated to prayer, after which ”only the two names which in the previous rounds had the highest number of votes will be considered, and the provision of a two third majority of the Cardinals present and voting for a valid election will remain.” The Motu proprio  also states that these two candidates cannot vote in subsequent ballots. These are the most recent rules for a conclave and therefore will be the ones observed for this conclave of 2013.

Previously, for the first three days of a conclave, a two-thirds majority was required for the election of a new pope. For example, if there are 99 voting Cardinals, the winner of the election must receive 66 or more votes. If the number of cardinals is not divisible by 3, the election is won by two thirds plus one vote.

If a new pope is not elected in a particular Scrutiny, a new balloting session began immediately. Two balloting sessions would be held in the morning, and two in the afternoon. There was only one balloting session on the first day of a conclave.

These rules changed if no new pope has been elected after three days. At that time, voting was suspended for a maximum of one day to give the Cardinals an opportunity for prayer, informal discussion, and instruction by the senior Cardinal in the Order of Deacons.

If another seven ballots produced no election, a second pause for prayer and discussion take place, including instruction by the senior Cardinal in the Order of Priests.

After a third set of seven ballots that had not produced an election, the senior Cardinal in the Order of Bishops instructed the Cardinals.

If, after seven more ballots, there was still no election of a new pope, the Cardinal electors were invited to discuss the manner of proceeding. There were two options:

• balloting continued, with the winner receiving an absolute majority (more than half) the vote
• balloting continued with only the top two candidates from the ballot immediately preceding this one, with the winner receiving an absolute majority (more than half) the vote

The decision between these two forms of balloting was decided by an absolute majority.