First, in stage one, Church authorities examine “the life of a candidate for sainthood.” The process, which generally may only begin five years after a candidate’s death, is first enacted at the diocesan or eparchial level.
After receiving a petition, consulting with the episcopal conference and the local faithful, and permission from the Holy See, the bishop will convene a tribunal, which will investigate the life of the candidate (or his/her potential martyrdom). “Witnesses will be called and documents written by and about the candidate must be gathered and examined,” the USCCB notes.
The diocese subsequently sends its report on to the Dicastery for the Causes of Saints; nine theologians subsequently “vote on whether or not the candidate lived a heroic life or suffered martyrdom.”
If they vote favorably, and after an examination by cardinals and bishops who are members of the dicastery, the prefect of the dicastery “presents the results of the entire course of the cause to the pope,” who gives his approval and directs the congregation to draft a decree declaring the candidate either Venerable (if ”they have lived a virtuous life”) or a Blessed (“if they have been martyred”).
In stage two, a Venerable is beatified when he or she has “a miracle attributed to [his or her] intercession.” The miracle “must be proven through the appropriate canonical investigation.” Upon beautification, a Venerable is given the title Blessed (that title is automatically granted to a martyr upon determination of his or her martyrdom).
In stage three, a Blessed is officially canonized with the determination of another miracle “attributed to the intercession of the Blessed and having occurred after his or her beatification.”
Canonization “allows for the public veneration of the saint by the universal Church,” the USCCB notes.
The two most recent saints canonized by the Church are Sts. Artemide Zatti and Giovanni Battista Scalabrini, with Pope Francis “enroll[ing] them among the saints” in October of last year.