The following information, provided by the U.S. Conference of Catholic Bishops, explains the steps involved in a Cause for Canonization.
Stage I – Examining the Life of a Candidate for Sainthood
Phase 1: Diocesan or Eparchial Level – Five years must pass from the time of a candidate's death before a cause may begin. This is to allow greater balance and objectivity in evaluating whether the candidate enjoys a true and widespread reputation of holiness and of intercessory prayer, distanced from the emotions of the person’s life and death. The pope can dispense from this waiting period. The bishop of the diocese or eparchy in which the person died is responsible for beginning the investigation. The petitioner (who, for example, can be the diocese/eparchy, bishop, religious order or association of the faithful) asks the bishop through a person known as the postulator to open the investigation. Once a cause is officially begun by the Bishop, the candidate may be called a “servant of God.”
The bishop then begins a series of consultations with the episcopal conference, the faithful of his diocese or eparchy, and the Holy See. Once these consultations are done and he has received the 'nihil obstat' of the Holy See, he forms a diocesan or eparchial tribunal. The tribunal will investigate the martyrdom or how the candidate lived a life of heroic virtues – that is, the theological virtues of faith, hope and charity; and the cardinal virtues of prudence, justice, temperance and fortitude, and others specific to his or her state in life. Witnesses will be called and documents written by and about the candidate must be gathered and examined.
Phase II: Congregation for the Causes of Saints – Once the diocesan or eparchial investigation is finished, the documentation is sent to the Congregation for the Causes of Saints. The postulator for this phase, residing in Rome, under the direction of a member of the Congregation's staff called a relator prepares the 'Positio,' or summary of the documentary evidence from the diocesan or eparchial phase in order to prove the heroic exercise of virtue or the martyrdom.
The 'Positio' undergoes an examination by nine theologians who vote on whether or not the candidate lived a heroic life or suffered martyrdom. If the majority of the theologians are in favor, the cause is passed on for examination by cardinals and bishops who are members of the Congregation. If their judgment is favorable, the prefect of the Congregation presents the results of the entire course of the cause to the pope, who gives his approval and authorizes the Congregation to draft a decree declaring one Venerable if they have lived a virtuous life or a Blessed if they have been martyred.
Stage II – Beatification
For the beatification of a Venerable, a miracle attributed to his or her intercession, verified after his or her death, is necessary. The required miracle must be proven through the appropriate canonical investigation, following a procedure analogous to that for heroic virtues. This investigation also is concluded with the appropriate decree. Once the decree on the miracle is promulgated, the pope grants the beatification, which is the concession of limited public veneration – usually only in the diocese, eparchy, region or religious community in which the Blessed lived. With beatification the candidate receives the title of Blessed. For a martyr, no miracle is required. When the pope approves the positio declaring that the person was a martyred for the faith, the title Blessed is granted to the martyr at that time.
Stage III – Canonization
For canonization, another miracle is needed for both Blessed martyrs and Blesseds who lived a virtuous life, attributed to the intercession of the Blessed and having occurred after his or her beatification. The methods for affirming the miracle are the same as those followed for beatification. Canonization allows for the public veneration of the Saint by the Universal Church. With canonization, the Blessed acquires the title of Saint.