Exorcism in the Catholic Church is not something that is “presumed” from dramatic signs alone. The Church’s criteria are primarily discernment and prudence: the request must concern a case where there is a serious indication of the Evil One’s direct action (demonic possession/dominion) rather than an illness—and, if a major (solemn) exorcism is needed, it must be done with the proper ecclesiastical authorization. 1 2 3

Who determines “necessity” and what role dicasteries have

In practice, the local Ordinary (diocesan bishop) governs exorcism ministry and authorizes it. Canon law requires special permission from the local Ordinary, and it is to be granted only to suitable priests (piety, knowledge, prudence, integrity of life). 2

Correspondingly, the CDF’s disciplinary norms stress that exorcism must be exercised in strict dependence on the diocesan bishop. 3

Regarding “Catholic dicasteries” and supernatural discernment more broadly: the Dicastery for the Doctrine of the Faith (in the 2024 norms for alleged supernatural phenomena) reaffirms that neither the diocesan bishop, nor episcopal conferences, nor the dicastery will ordinarily declare that such phenomena are of supernatural origin, even when a nihil obstat is granted; only the Holy Father can authorize a special procedure. 4

So, dicasteries do not typically “certify possession” in the way local ministry does; they regulate and clarify norms, while discernment remains ecclesial and hierarchical. 4 3

What counts as a sufficient basis: “genuine demonic possession” (major exorcism)

The Catechism distinguishes exorcism from medical treatment and provides a clear criterion for when a solemn rite belongs:

• Exorcism is the Church’s public, authoritative prayer that a person or object be protected from the power of the Evil One and withdrawn from his dominion. 1
• A major exorcism (“solemn exorcism”) can be performed only by a priest with the permission of the bishop, and the priest must proceed with prudence, strictly following Church rules. 1
• Crucial criterion: before an exorcism is performed, it is important to ascertain that one is dealing with the presence of the Evil One, not an illness (especially psychological illness). 1

The US bishops’ summary of exorcism practice makes the same core point in pastoral terms: the Rite of Major Exorcism is used only when there is a case of genuine demonic possession, “namely” when it is determined that the presence of the devil is in the body of the possessed and the devil is able to exercise dominion over it. 5

Thus, “necessity” is not primarily based on fear, superstition, or anecdotal claims, but on whether—after discernment—there is evidence consistent with the Church’s understanding of demonic possession/dominion. 5 1

What must be ruled out: illness, psychological disorders, and the need for thorough assessment

A defining criterion in Catholic discernment is not confusing demonic influence with sickness. The Catechism explicitly says that illness—especially psychological illness—is “a very different matter” and belongs to medical science; therefore, the Church must first ascertain that the case is not illness. 1

The US bishops further explain the discernment process recommended in diocesan protocols:

• An assessment should determine the true state of the person.
• Only after a thorough examination, including medical, psychological, and psychiatric testing, should the person be referred to the exorcist for a final determination regarding demonic possession. 5

This is the practical “criteria” dimension: exorcism becomes a serious possibility only after the Church’s process has taken health explanations seriously and extensively. 5 1

How Church rules prevent “false positives”: proper form and careful boundaries

The Church also sets safeguards about what may and may not be done liturgically:

• The CDF instruction on healing prayers states that exorcism ministry must be exercised properly and that the prayers of exorcism in the rite must remain separate from healing services (liturgical or non-liturgical). 3
• It is absolutely forbidden to insert exorcism prayers into the celebration of Mass, the sacraments, or the Liturgy of the Hours. 3

In other words, even when spiritual concern is real, the Church avoids turning exorcism into a generic “spiritual treatment” that blurs boundaries and increases the risk of misunderstanding illness as demonic causation. 3 1

Authorization and who may perform exorcism

Even if discernment suggests demonic possession, “necessity” still does not bypass canonical authorization:

• Canon law requires special and express permission from the diocesan Ordinary for those who perform exorcisms over the possessed. 2
• Major exorcism belongs to the category of solemn exorcism and is performed by an authorized priest/bishop with that permission. 5 1
• The CDF norms reiterate the ministry’s strict dependence on the diocesan bishop. 3

Therefore, the criterion is twofold:

1. substantive discernment (presence of the Evil One/demonic dominion rather than illness), and
2. canonical competence (permission and proper authorization). 1 2 3

Summary of the criteria (as Catholic norms express them)

• There must be evidence consistent with “the presence of the Evil One,” not an illness—especially psychological illness. 1
• Rule out medical/psychological/psychiatric explanations through a thorough assessment before referring for possible major exorcism. 5
• Major exorcism is reserved for genuine demonic possession, defined in terms of the devil’s dominion over the body. 5
• Proper Church boundaries and form must be respected (exorcism prayers are separate from healing rites; cannot be inserted into Mass/sacraments/Liturgy of Hours). 3
• The diocesan bishop’s authorization is required, and exorcism ministry is exercised in strict dependence on him. 2 3
• Dicasteries generally do not declare supernatural origin as a rule; local discernment and hierarchical authorization govern, with only the Holy Father able to authorize special procedures. 4