Fiction about people being possessed by demons?

Read the first 30-40 pages at least 10 years ago (more likely 15-20).
Set in a present where demons have recently started possessing people and doing bad stuff, and society is aware of it.
The main character gets possessed and rapes a girl. He is arrested and charged because demons were thought to stay away from pharmacies (the location of the rape). During his trial, the judge gets possessed herself, and the guy's lawyer suggests that he confess, to escape death penalty. So instead he is branded and sent to some remote location... and this is where I stopped reading.
The book has stayed with me for all these years, I really want to read it. Thanks.

Possibly A Plague of Pythons by Frederik Pohl, (v.t. Demon in the Skull, says Wikipedia). I can't confirm any of the details except the assault and trial, though - it's been a long time since I read it.

Thanks Dukedom, looks like that might be it - I will pick it up and confirm.
Unfortunately, while trying to figure out if it was the right book, I think I read a spoiler...
Thanks again.

I looked at my copy of Plague. Substitute a pharmaceuticals plant for a pharmacy, and the jury forewoman for the judge as the possessed one at the trial, and it's a match.

And a good book, if I recall correctly.