Criteria for evaluating apparitions
In 1978 the Sacred Congregation for the Doctrine of the Faith (formerly of the Holy Office) issued "Norms of the Congregation for Proceeding in Judging Alleged Apparitions and Revelations" containing the following provisions:
The diocesan bishop can initiate a process on his own initiative or at the request of the faithful to investigate the facts of an alleged apparition. The bishop may refrain from looking into it if he chooses, especially if he thinks that not much will come of the event.
The national conference of bishops may intervene if the local diocesan bishop refers it to him or if the event becomes important nationally or at least in more than one diocese.
The Apostolic See (the Vatican) can also intervene at the request of the local bishop himself, at the request of a group of the faithful, or on its own initiative.
The steps of the investigation are mandated as follows: An initial evaluation of the facts of the alleged event, based on both positive and negative criteria:
moral certainty (the certainty required to act morally in a situation of doubt) or at least great probability as to the existence of a private revelation at the end of a serious investigation into the case
evaluation of the personal qualities of the person in question (mental balance, honesty, moral life, sincerity, obedience to Church authority, willingness to practice faith in the normal way, etc.)
evaluation of the content of the revelations themselves (that they do not disagree with faith and morals of the Church, freedom from theological errors)
the revelation results in healthy devotion and spiritual fruits in people's lives (greater prayer, greater conversion of heart, works of charity that result, etc.)
glaring errors in regard to the facts
doctrinal errors attributed to God, the Blessed Virgin Mary, or to the Holy Spirit in how they appear
any pursuit of financial gain in relation to the alleged event
gravely immoral acts committed by the person or those associated with the person at the time of the event
psychological disorders or tendencies on the part of the person or persons associated
After this initial investigation, if the occurrence meets the criteria, positive and negative, an initial cautionary permission can be granted that basically states: "for the moment, there is nothing opposed to it". This permits public participation in the devotion in regard to the alleged apparition.
Ultimately, a final judgment and determination needs to be given, giving approval or condemnation of the event.