Classifying books according to their suitability for different age ranges would be “ill-advised”, “unworkable” and would “raise serious concerns about censorship”, American free-speech campaigners have said, in the wake of a poll claiming that more than seven in 10 US adults believe a rating system similar to that used for films should be applied to books.

The Harris poll of 2,244 US adults was released in July, revealing that, in the space of four years, the percentage of Americans believing that some books should be completely banned has increased by more than half. In 2011, 18% of those surveyed wanted some books banned; in 2015, 28% agreed with the assertion. Just under a half, 48%, said that no books should be banned, compared with 56% in 2011.

Republicans, the poll found, are nearly twice as likely as Democrats to believe some books should be banned, with 42% agreeing with the claim compared with 23% of Democrats.

In recent months, parents in Idaho have asked for John Steinbeck’s Of Mice and Men to be removed from classrooms, concerned over profanities such as “bastard” and “God damn”, while in Florida, parents have tried to ban two children’s books respectively set in Afghanistan and Iraq, citing violent content and their inclusion of religions other than Christianity.

Idaho parents push for schools to ban Of Mice and Men for its 'profanities' Read more

Almost two-thirds (60%) of Americans, according to the poll, felt children should not be able to borrow books containing explicit language from libraries, with 33% feeling they should. Forty-eight per cent wanted to block children’s school-library access to books containing reference to violence, while 45% felt children should be able to access such books. A third said the Koran should not be in school libraries, but 55% felt it should; 26% were against school libraries featuring books “that question the existence of a divine being or beings”, but 66% felt such book they should be available.

The idea of rating books – raised in the UK in 2008 to overwhelming opposition from authors including Philip Pullman and JK Rowling – was supported by more than two-thirds of Americans, according to the poll, with 71% agreeing with the statement that “there should be a rating system for books (as there are for films, TV shows, and video games)”.

But Joan Bertin, executive director of the National Coalition Against Censorship, said that “age-ratings systems for books are ill-advised and unworkable”, because “they are based on highly subjective judgments that seek to reduce complex works to a few letters or numbers, and that assume that age is all that matters in determining what reading matter is suitable for any given person”.

“When extended to public settings like libraries and schools, reliance on any rating system that selectively identifies specific content or ideas in literary works would raise serious concerns about censorship,” said Bertin. She added that, while “thankfully there is no serious interest in the publishing industry to concoct a book ratings system in [the US]”, there are “a proliferation of privately run websites”, including Common Sense Media, Compass Book Ratings and The Literate Mother, which identify material containing content such as sex or violence. “Even these efforts invite censorship efforts by parents who cite them to object to books assigned in schools; we have found that some teachers and librarians also rely on them, perhaps for their assessments of the books and perhaps to avoid material that might elicit complaints. If school officials rely on these sites in deciding to remove a book, it would raise constitutional questions,” said Bertin.

Common Sense Media, however, says its approach is “about sanity, not censorship”, and that it provides “information about content for parents, educators, kids so that they can make informed decisions for themselves about what they’d like to watch, read, play”. The Literate Mother says its goal is to “provide reliable content ratings for youth and young adult literature”, with books it covers “read and objectively rated in four categories: language, violence, sexual content and adult themes”.

“This information helps parents and concerned adults suggest or discourage certain books, discuss sensitive material or simply strike up a conversation with a child about the book he or she is reading. Whether you have a sensitive child who you want to steer away from certain topics, a voracious reader you would like to guide toward more appropriate books, or just want to be informed on the subject matter to which your young reader is exposed, we hope you will find help,” says the site.

Authors and librarians in the UK put up strong resistance to publishers’ 2008 proposals to add age bands to children’s books, with Philip Pullman labelling age-ranging a “piece of dishonesty”. But publishers such as Random House, Oxford University Press and HarperCollins have been publishing some UK editions with age guidance ever since.

Librarians oppose age recommendations for books Read more

At the Association of American Libraries, which tracks challenges to books throughout the year, Kristin Pekoll, assistant director of the office for intellectual freedom, was not surprised by the support for ratings, but did not see them as a solution to concerns. “The support for ratings is not surprising. Many people are looking for security that they won’t be offended or [made] uncomfortable. Rating books won’t do that. Even with the cleanest rating, a person can still be offended. Because people are unique and books are complex. No rating system is going to convey everything in a book. To do that you need to read the book and decide for yourself,” she said.

“The spirit of democracy is free choice, debate and critical thinking. We want individuals not robots. Ratings allow other people to make choices and restrictions for you based on criteria that you may or may not value. Thankfully, we live in a country where the first amendment guarantees our right to do that.”