In Copyright, we read a case about Harry Potter. See Warner Bros. Entm't Inc. v. RDR Books, 575 F. Supp. 2d 513 (S.D.N.Y. 2008). The case is about the planned publication of a book called The Lexicon. Online, the Lexicon was a Harry Potter fansite slash wiki like Wookiepedia. So Warner Brothers sued the publisher before they published the Lexicon in book form. Because "Just Kidding" Rowling planned on releasing her own encyclopedia. "Rowling has stated on a number of occasions since 1998 that, in addition to the two companion books, she plans to publish a 'Harry Potter encyclopedia' after the completion of the series and again donate the proceeds to charity." Id. at 519 (emphasis added).
That's all boring case brief stuff. But THIS is the interesting part! Most of the opinion concerns the Lexicon lifting passages direct from the books. The court quotes from entries on the site, including the entry on Dementors. So, according to a block quote from the Lexicon, "'[t]he Ministry used Dementors as guards in its courtrooms . . . .'" Id. at 528.
So they don't let trolls in dungeons, but they let DEMENTORS WORK IN THE COURTROOM? And collect a PAYCHECK? As a GOVERNMENT EMPLOYEE?? With MY TAX DOLLARS???
According to the Harry Potter Wiki, this wasn't made up whole-cloth by some rogue mod. "During the 1997 infiltration of the Ministry of Magic, while Harry Potter was disguised as Albert Runcorn, he encountered the Dementors in the Muggle-Born Registration Commission courtroom, where they were used to take away convicted Muggle-borns after interrogation and to terrorise them during interrogation." The wiki cites Harry Potter and the Deathly Hallows as its source, but not a page number. That ain't a correct Bluebook citation, brother! There's also this picture:
I do not remember this scene from either the book or the film. Films? I tried a reverse-image search and couldn't see if this scene was in Part 1 or Part 2. But I did find a Quora question about the Ministry controlling Bailiff Dementors. According to Jimmy Gill, System Administrator at Boeing (2012-present), "[t]he Dementors obey the Minister because his government ensures a steady supply of victims for them to feed on."
Straight from the horse's mouth.