'The Choirboys' title is derived from the activities of the story's police officers which they call "choir practices" - these are drunken parties that the cops throw in order to let off steam from the stress and pressure of their jobs.
A number of the names of characters were changed from the source novel for this filmed adaptation: Sam Niles to Sam Lyles (Don Stroud), Calvin Potts to Calvin Motts (Louis Gossett Jr.), Father Willie Wright to 'Father' Sartino (Chuck Sacci) and Dean Pratt became Dean Proust (Randy Quaid).
Novelist Joseph Wambaugh disowned, disavowed and de-credited himself from this filmed adaptation of his book 'The Choirboys'. Wambaugh was so incensed with the adaptation of his book, considering it to be such a poor adaption, that he sued the production and was successful in having his name removed from the film's credits.
After the way his novel was adapted for this film, novelist Joseph Wambaugh decided to take more control of his literary works, having a much larger influence on the production of The Black Marble (1980) and The Onion Field (1979).
This movie was made and released about two years after its source novel of the same name by Joseph Wambaugh was first published in 1975. 'The Choirboys' was Wambaugh's fourth novel. In 1995, the book was included as the Number 93 title in The Top 100 Crime Novels of All Time by the Mystery Writers of America.