Novels like To Kill a Mockingbird, which have sexist and racist themes, can convincingly plead historical significance, but sexual content, homosexuality, and profanity have a harder time. It can quickly become a political debate, usually with conservative parents fighting for library-shelf editing.
But liberal parents, accustomed to arguing to endless freedom of the press, have found themselves on another page the last few years. Twilight became the fifth most complained about book of 2009 because of its religious, abstinence-until-marriage message. The series got such a bad reputation that Cambridge University studied its effects on teens and found it discourages independent thinking and personal development, and the passive heroine Bella is a bad role model for teen girls.
Is there ever a good reason to ban a book, like its negative effects have been scientifically proven, or is the slope way too slippery for you?