The Catholic Church investigates a reported miracle by one of three procedures, depending on the kind of claim. A healing proposed in a saint's cause is investigated first by the local bishop, then in Rome by a board of physicians, who must conclude by a qualified majority (at least five of seven) that it cannot be explained scientifically, then by theologians and by cardinals and bishops, before the Pope authorizes a decree. A cure at Lourdes passes through the sanctuary's Medical Bureau and an international medical committee and is declared by a bishop. Reported apparitions, weeping images and Eucharistic phenomena are examined by the diocesan bishop under norms issued in 2024, and his conclusion needs the approval of the Dicastery for the Doctrine of the Faith.
In each procedure the medical and the theological questions are kept apart: doctors establish what happened and whether medicine can account for it, and the Church judges what it means. For a healing in a saint's cause the medical board asks whether the recovery was rapid, complete, lasting and scientifically unexplained. Regulations issued in 2016 for the board allow a case to be examined no more than three times.
The Lourdes procedure, in which the international committee may find a cure "medically unexplained in the current state of scientific knowledge" before a bishop decides, is set out step by step in the answer on the recognized miracles of Lourdes.
The 2024 Norms add that Church authorities will not, as a rule, declare an apparition or similar phenomenon supernatural; the most favourable ordinary outcome is a nihil obstat permitting devotion. Of such phenomena the Norms say that "the faithful are not obliged to give an assent of faith to them." The answer on how approval of apparition sites works lists the six possible outcomes.
A claim's popularity is not a judgment of the Church. What counts is what the competent authority has actually declared, and about what.
Related questions, answered
What miracles were recognized for St. Carlo Acutis?
For his beatification, the healing of a child in Brazil who had a congenital malformation of the pancreas; the diocesan inquiry was held in the Archdiocese of Campo Grande, the medical board judged the healing rapid, complete, lasting and scientifically unexplained in November 2019, and Pope Francis authorized the decree in February 2020. For his canonization, the recovery of a young Costa Rican woman who suffered a severe head injury in Florence in 2022. He was canonized on 7 September 2025.
Source: Dicastery for the Causes of Saints: Carlo Acutis (biography, cause and the two recognized miracles; Italian)
