Exorcism
In Catholic Christianity, exorcisms are performed in the name of Jesus Christ. A distinction is made between a formal exorcism, which can only be conducted by a priest during a baptism or with the permission of a bishop, and "prayers of deliverance" which can be said by anyone.
The Catholic rite for a formal exorcism, called a "Major Exorcism", is given in Section 11 of the Rituale Romanum. The Ritual lists guidelines for conducting an exorcism, and for determining when a formal exorcism is required. Priests are instructed to carefully determine that the nature of the affliction is not actually a psychological or physical illness before proceeding.
Exorcism
The Jewish exorcism ritual is performed by a rabbi who has mastered practical Kabbalah. Also present is a minyan (a group of ten adult males), who gather in a circle around the possessed person. The group recites Psalm 91 three times, and then the rabbi blows a shofar (a ram's horn).