Board of Education, Island Trees School District v. Pico
457 U.S. 853 (1982), restricted the ability of school boards to censor school libraries. The Court, in reversing a New York state decision that allowed a local school board to remove books it found offensive, ruled that while a board may exercise a certain amount of discretion in creating a library to reflect community values, it cannot arbitrarily impose its own will on the effort and trample citizens' First Amendment rights. Books that can be shown to be vulgar or irrelevant may be removed, but books that simply contain unpopular ideas may not be.
Seen and Heard
What made you want to look up Board of Education, Island Trees School District v. Pico? Please tell us where you read or heard it (including the quote, if possible).