2. Make sure the person isn’t simply crazy.

Learned from: The Exorcism of Emily Rose (2005)

Complex says: Based on true events, The Exorcism of Emily Rose is more of a courtroom drama than a spook-fest, depicting the heated lawsuit against a priest after an exorcism results in the said-to-be possessed girl’s death. We can’t imagine too many lawyers would jump at the chance to defend an exorcist. Would burnt crucifixes work as evidence? How about tape recordings that sound like Black Sabbath records played backwards? Those are legal inquiries best left alone, so the first thing a demon-fighter should do before actually fighting demons is perform an extensive background check.