It happens in the United States more often than many realize. At least 464 formal complaints were filed in 2012 seeking to remove books from libraries or schools, according to the American Library Association, a sponsor of Banned Books Week, which runs September 22-28. Its mission is to celebrate the freedom to read and highlight the pitfalls of censorship.

The annual event started in 1982, the same year the Supreme Court ruled that students' First Amendment rights were violated when Kurt Vonnegut's "Slaughterhouse-Five" and eight other books were removed from school libraries. Despite the legal precedent, schools and libraries still receive formal challenges to remove books from library shelves or nix them from reading lists to protect children from material some see as inappropriate.

Just this month, a North Carolina school board voted to ban Ralph Ellison's "Invisible Man" based on complaints from the parent of an 11th-grader. The board is reportedly scheduled to reconsider its decision.