Why did the film Kings Row have to change parts of Henry Bellamann’s novel?

The film Kings Row (1942), directed by Sam Wood, had to alter significant portions of Henry Bellamann’s novel to comply with the Hays Code, a strict set of moral guidelines governing the American film industry at the time.1

The Code mandated that motion pictures must not lower the moral standards of the audience or create sympathy for wrongdoing, evil, or sin. Because Bellamann’s novel contained mature themes—including sexual indiscretions, complex psychological issues, and controversial social behaviors—filmmakers were required to sanitize the narrative. Under the Code’s strict oversight, any depiction of "disreputable behavior" had to be handled carefully, often requiring that the plot unequivocally condemn such actions to ensure that "correct standards of life" were presented. Consequently, the adaptation had to soften or omit elements that the censors deemed offensive or contrary to the moral obligations of the era.1