I know it when I see it
The phrase "I know it when I see it" is a colloquial expression by which a speaker attempts to categorize an observable fact or event, although the category is subjective or lacks clearly defined parameters. The phrase was famously used in this sense by United States Supreme Court Justice Potter Stewart to describe his threshold test for obscenity in Jacobellis v. Ohio (1964). In this case obscenity was protected speech under the Roth test, and could not therefore be censored.
I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description ["hard-core pornography"]; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that. [Emphasis added.]
The expression became one of the most famous phrases in the entire history of the Supreme Court.
A well-known use of this phrase is found in Goldfinger, when M asks Bond: "What do you know about gold?" and Bond replies with "I know it when I see it.". However, this sentence is already found in the novel of the same name, but since the movie had its premiere just a few months after Stewart's use of this phrase, it became even more popular because of the movie.
The Supreme Court of the United States' rulings concerning obscenity in the public square have been unusually inconsistent. Though First Amendment free speech protections have always been taken into account, both Constitutional "Interpretationalists" and "Originalists" have limited this right to account for public sensibilities. Before Roth v. United States in 1957, common law rules stemming from the 1868 English case Regina v. Hicklin have articulated that anything which "deprave[s] and corrupt[s] those whose minds are open to such immoral influences" was said to be obscene, and therefore banned. The Roth case gave a clearer standard for deciding what constitutes pornography, stating that obscenity is material where the "dominant theme taken as a whole appeals to the prurient interest", and that the "average person, applying contemporary community standards" would disapprove of, reaffirming the 1913 case United States v. Kennerley. This standard allowed for many works to be called obscene, and though the Roth decision acknowledged "all ideas having even the slightest redeeming social importance [...] have the full protection of guaranties [sic]", the Justices put public sensibility above the protection of individual rights.
Jacobellis v. Ohio (1964) narrowed the scope of the Roth decision. Justice Potter Stewart, in his concurrence to the majority opinion, created the standard whereby all speech is protected except for "hard-core pornography". As for what, exactly, constitutes hard-core pornography, Stewart said "I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description, and perhaps I could never succeed in intelligibly doing so. But I know it when I see it, and the motion picture involved in this case is not that."
This was modified in Memoirs v. Massachusetts (1966), in which obscenity was defined as anything patently offensive, appealing to prurient interest, and of no redeeming social value. Still, however, this left the ultimate decision of what constituted obscenity up to the whim of the courts, and did not provide an easily applicable standard for review by the lower courts. This changed in 1973 with Miller v. California. The Miller case established what came to be known as the Miller Standard, which clearly articulated that three criteria must be met for a work to be legitimately subject to state regulations. The Court recognized the inherent risk in legislating what constitutes obscenity, and necessarily limited the scope of the criteria. The criteria were:
- The average person, applying local community standards, looking at the work in its entirety, appeals to the prurient interest.
- The work must describe or depict, in an obviously offensive way, sexual conduct, or excretory functions.
- The work as a whole must lack "serious literary, artistic, political, or scientific values".
See also 
- Paul Gewirtz, "On 'I Know It When I See It'", Yale Law Journal, Vol. 105, pp. 1023–1047 (1996)
- Harry Kalven, Jr., A Worthy Tradition: Freedom of Speech in America, p. 40 (1988)
- Richard A. Posner, Law and Literature: A Misunderstood Relation p. 308 (1988)
- http://www.script-o-rama.com/movie_scripts/g/goldfinger-script-transcript-james-bond.html Dialogue Transcript of Goldfinger
- Roth v. United States. The Oyez Project at IIT Chicago-Kent College of Law. 8 February 2012. <http://www.oyez.org/cases/1950-1959/1956/1956_582>.
- Jacobellis v. Ohio. The Oyez Project at IIT Chicago-Kent College of Law. 8 February 2012. <http://www.oyez.org/cases/1960-1969/1962/1962_11_2>.