Codex Iuris Canonici (CIC)
Can. 1172 §1. No one can perform exorcisms legitimately upon the possessed unless he has obtained special and express permission from the local ordinary.
§2. The local ordinary is to give this permission only to a presbyter who has piety, knowledge, prudence, and integrity of life.
Catechism of the Catholic Church (CCC)
550 The coming of God's kingdom means the defeat of Satan's: "If it is by the Spirit of God that I cast out demons, then the kingdom of God has come upon you."277 Jesus' exorcisms free some individuals from the domination of demons. They anticipate Jesus' great victory over "the ruler of this world".278 The kingdom of God will be definitively established through Christ's cross: "God reigned from the wood."279
⇒ Mt 12:26,
278 ⇒ Jn 12:31; cf. ⇒ Lk 8:26-39.
279 LH, Lent, Holy Week, Evening Prayer, Hymn Vexilla Regis: Regnavit a ligno Deus.
1237 Since Baptism signifies liberation from sin and from its instigator the devil, one or more exorcisms are pronounced over the candidate. the celebrant then anoints him with the oil of catechumens, or lays his hands on him, and he explicitly renounces Satan. Thus prepared, he is able to confess the faith of the Church, to which he will be "entrusted" by Baptism.39
1673 When the Church asks publicly and authoritatively in the name of Jesus Christ that a person or object be protected against the power of the Evil One and withdrawn from his dominion, it is called exorcism. Jesus performed exorcisms and from him the Church has received the power and office of exorcizing.176 In a simple form, exorcism is performed at the celebration of Baptism. the solemn exorcism, called "a major exorcism," can be performed only by a priest and with the permission of the bishop. the priest must proceed with prudence, strictly observing the rules established by the Church. Exorcism is directed at the expulsion of demons or to the liberation from demonic possession through the spiritual authority which Jesus entrusted to his Church. Illness, especially psychological illness, is a very different matter; treating this is the concern of medical science. Therefore, before an exorcism is performed, it is important to ascertain that one is dealing with the presence of the Evil One, and not an illness.177
177 Cf. ⇒ CIC, can. 1172.