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.

These procedures were believed to be in keeping with the Supreme Court's recent Marcus v. Search Warrant decision, which held that some sort of judicial review was necessary to determine if seized material was obscene prior to seizure.

Justice William Brennan wrote for a four-justice plurality that considered the case strictly on procedural grounds, without reaching the question of the books' obscenity.

In one of two separate concurrences, Justice Hugo Black reaffirmed his earlier blanket opposition to all legal suppression of obscenity, in which he was joined by William O. Douglas.

In dissent, Justice John Marshall Harlan II wrote for himself and Tom Clark in faulting Brennan's application of the precedents he relied on.

That began to change during the 20th century, in response to social and cultural trends of greater tolerance for literature and art that depicted such proscribed material.

In the landmark 1933 case United States v. One Book Called Ulysses, Judge John M. Woolsey of the Southern District of New York ruled that James Joyce's novel Ulysses, chapters of which had been held obscene over a decade earlier when published in a literary review, could not be barred from the United States purely on the basis of its language and content without considering its literary merit.

[1] Second Circuit judges Learned and Augustus Hand upheld Woolsey on appeal,[2] and the book, considered a masterpiece of modernist literature, could be freely published and sold.

[3] Justice William Brennan wrote for a 6–3 majority that upheld the criminal conviction but abandoned the century-old Hicklin test in favor of a narrower definition of obscenity.

In 1961, the Court had heard Marcus v. Search Warrant, in which several bookstores in Kansas City, Missouri, had challenged the seizure of some of their wares prior to any hearing at which they could contest the finding of obscenity.

P–K moved to have the information and the warrant quashed on the grounds that, since they had not been afforded a hearing on the obscenity question prior to the seizure, their constitutional rights had been violated.

He relied on both Marcus and Kingsley Books Inc. v. Brown, a 1957 case in which a bookstore had unsuccessfully challenged a statute allowing the state to obtain a temporary injunction against the sale of allegedly obscene material.

'"[9] Stewart alluded to his concurring opinion in Jacobellis v. Ohio, Quantity of Books's companion case, where he had said that only "hardcore pornography", which he memorably declined to define beyond "I know it when I see it",[10] was beyond First Amendment protection.

He pointed to the extensive review by the judge before he granted the warrant, as well as its limitations to only the titles named in it, two controls which had been absent in Marcus and were specifically imposed by Ferguson in response to the later decision.

The New York statute upheld in Kingsley Books had allowed for an almost immediate hearing after the granting of the injunction, but he considered it unlikely that any defendant or claimant would be able to prepare a defense that quickly.

"In pragmatic terms, then, the nature of the restraint imposed by the Kansas statute is not in a constitutionally significant sense different from that sustained in Kingsley Books.

[16] In the next term, the Court would use Quantity of Books to bolster its holding against a state film-licensing system in Freedman v. Maryland, as one of several in which it had held that only an adversary hearing prior to restraint sufficed to protect First Amendment rights.

[18] The next year, by contrast, Maryland district judge Roszel Cathcart Thomsen, hearing a bench trial of a man accused of transporting obscene materials across state lines, rejected his argument that the search of his vehicle which produced the two movies at issue had been unconstitutional under Quantity of Books.

Thomsen distinguished the two cases with two factors: the Maryland one had involved materials stored in a vehicle rather than a warehouse, and, in it, the defendant was seeking merely to suppress them as evidence rather than contesting a forfeiture.