Guidelines from The Roman Ritual

- Possession is not to be taken lightly. Each case is to be carefully examined and great caution is to be used in distinguishing genuine possession from certain forms of disease.

- The priest who undertakes the office should be himself a holy man, of a blameless life, intelligent, courageous, humble, and he should prepare for the work by special acts of devotion and mortification, particularly by prayer and fasting (Matthew 17:20).

- He should avoid in the course of the rite anything resembling superstition and he should leave the medical aspects of the case to qualified physicians.

- He should admonish the possessed, insofar as the latter is capable, to dispose himself for the exorcism by prayer, fasting, confession and communion.

- The exorcism should take place in the church or some other sacred place, if convenient; but if on account of sickness or for other legitimate reasons, it takes place in a private house, witnesses (preferably members of the family) should be present: this is specially enjoined, as a measure of precaution, in case the subject is a woman.

- All idle and curious questioning of the demon should be avoided, and the prayers and aspirations should be read with great faith, humility and fervour, and with a consciousness of power and authority.

- The Blessed Sacrament, or the host, is not to be brought near the body of the obsessed during exorcism for fear of possible irreverence; but the crucifix, holy water, and, where available, relics of the saints are to be employed.

- If expulsion of the evil spirit is not obtained at once, the rite should be repeated, if need be, several times.

- The exorcist should be vested in cassock, surplice, and a violet stole.