This post was commissioned last year during Banned Books Week. United States v. Mark Twain No such case as my title implies was ever brought, of course. The United States has no banning—that is, no centralized prohibition of books. Here, a ban has come to mean any decision to eliminate a book from a library or a school reading list. It’s true that, until fairly recently, the Postal Service exercised a censoring function by enforcing laws against sending obscene matter through the mail. But Supreme Court decisions of the ’60s and ’70s have rendered obscenity pretty ungainly to work with as a criminal charge. Huckleberry Finn was “banned” several times in Mark Twain’s lifetime—always by librarians. In 1885, when the book was new, the public library in Concord, Massachusetts, withdrew it, citing the characters’ “low grade of morality” and “irreverence.” Huck lies, talks dialect, is friends with a black man, steals and fails to return stolen property (the black man). Mark Twain’s respon...