Quantity of Books v. Kansas, 378 U.S. 205 (1964), is an in rem United States Supreme Court decision on First Amendment questions relating to the forfeiture of obscene material. By a 7–2 margin, the Court held that a seizure of the books was unconstitutional, since no hearing had been held on whether the books were obscene, and it reversed a Kansas Supreme Court decision that upheld the seizure.