If there is a bedrock principle underlying the First Amendment, it is that the government may not prohibit the expression of an idea simply because society finds the idea itself offensive or disagreeable.
Justice William J. Brennan, Jr., writing for the majority in Texas v. Johnson, 491 U.S. 397 (1989)
The ALA makes a distinction between banned books (those officially removed) and challenged books (those that some individual or group wants to remove).
ALA says in its discussion of free access to libraries for minors,
Librarians and library governing bodies cannot assume the role of parents or the functions of parental authority in the private relationship between parent and child. Librarians and governing bodies should maintain that only parents and guardians have the right and the responsibility to determine their children’s — and only their children’s — access to library resources. Parents and guardians who do not want their children to have access to specific library services, materials, or facilities should so advise their children.
The strongest memory is weaker than the palest ink. From clay tablets to scrolls to codices to manuscripts to the First Folio to electronic books, we’ve captured ideas so as to make them available for others. It’s not a bad trend.