Miller v. California, 413 U.S. 15 (1973), was a landmark decision of the U.S. Supreme Court clarifying the legal definition of obscenity as material that lacks "serious literary, artistic, political, or scientific value".

[2] In 1971, Marvin Miller, owner of a California mail-order business specializing in pornographic films and books, mass-mailed a brochure advertising products that graphically depicted sexual activity between men and women.

[3] Miller was arrested and charged with violating California Penal Code 311.2(a) which says in part: "Every person who knowingly sends or causes to be sent, or brings or causes to be brought, into this state for sale or distribution, [...] any obscene matter is for a first offense, guilty of a misdemeanor.

"[4] California lawmakers wrote the statute based on two previous Supreme Court obscenity rulings:[5] Memoirs v. Massachusetts[6] and Roth v. United States.

[1] Miller appealed to the Appellate Division of the Superior Court, arguing that the jury instructions did not use the standard set in Memoirs v. Massachusetts which said that in order to be judged obscene, materials must be "utterly without redeeming social value.

Under the Comstock laws controlling mail distribution that prevailed before Roth, any material that tended to "deprave and corrupt those whose minds are open to such immoral influences" was deemed "obscene" and could be banned on that basis.

[1] Roth defined obscenity more strictly, as material whose "dominant theme taken as a whole appeals to the prurient interest" to the "average person, applying contemporary community standards".

Furthermore, due to the three-part test's stringent requirements, very few types of content can now be completely banned, and material that is appropriate for consenting adults can only be partially restricted per delivery method.

[15] In Ashcroft v. Free Speech Coalition in 2002, however, the Court held that sexually explicit material that only appears to depict minors, but actually does not, might be exempt from obscenity rulings.