Based on the true story of Anneliese Michel, a young German woman who suffered a similar fate to the fictional Emily Rose in the 1970s, and "The Exorcism of Anneliese Michel", an account of the subsequent court case by expert witness Felicitas D. Goodman, an anthropologist called in as an expert on possession. Michel's parents and the two priests who performed her exorcism were prosecuted, though the prosecution asked that the parents be excused from punishment as they had "suffered enough". Ultimately, the accused were found guilty of manslaughter resulting from negligence, and the two clergymen were sentenced to six months in jail (which was later suspended) and three years of probation. The most significant differences are that Michel periodically fasted for several months as part of her exorcism and remained on medication until her death, while the fictional Rose was incapable of eating due to demonic forces and decided herself to stop taking her medication with the consent of her care-providers. The story was heavily adapted for cinematic purposes.
There were two dolls constructed for this film. The first was where Emily Rose would lock her limbs. The other was during the dorm scene where she is on the floor in a twisted position. The director ultimately never used a doll in the dorm room scene because he found out that Jennifer Carpenter is double jointed, and decided that the positions she was able to contort herself into were more unsettling than what could be accomplished with the dummy. When Emily starts to bend over backwards in the church, Carpenter wore a harness to make the effect more inhuman.
Since this film's release, a persistent urban legend has sprung up amongst students at the University of Minnesota. According to the legend, Pioneer Hall, an allegedly haunted dormitory, was where Emily Rose was first "possessed," as seen in the film. However, as Emily Rose is a fictional version of Anneliese Michel, a German woman who never attended the U of M, this legend is obviously false.