On June 22, 1964, Justice Potter Stewart coined the phrase “I know it when I see it” in his concurring opinion in Jacobellis v. Ohio. Fifty years later, that expression holds the distinction of being one of the few modern legal phrases to become a regularly accepted expression among educated Americans. The half-century anniversary of Jacobellis provides a fitting opportunity to ask why “I know it when I see it” has enjoyed such popularity and what lessons that phrase and its history might hold for us today.
Jacobellis reversed the conviction of an Ohio movie theater manager for showing obscene material in the form of the French film Les Amants (The Lovers), which included a sex scene at its conclusion. The court’s 6-3 decision was highly fragmented, with six opinions in total and the plurality garnering only two votes.
In a short 144-word concurring opinion, Stewart wrote that he found it almost impossible to define obscenity precisely, which should only include “hard-core pornography.” His now famous line concluded the opinion:
“But I know it when I see it, and the motion picture involved in this case is not that.”
At the time, the pithy phrase actually garnered little interest in the public sphere. Many newspapers chose instead to focus on another obscenity case decided that same day, Quantity of Books v. Kansas. Those journalists who did write about Jacobellis largely ignored “I know it when I see it” and chose to focus on the legal technicalities the case posed.
While it is difficult to pinpoint exactly when Stewart’s iconic expression became common, we can chart its growing popularity via Google’s Ngram search engine. Google Ngram measures the percentage of English language books that contain a phrase up to five words long. Because “I know it when I see it” is seven words, I ran the search for each five-letter segment of the phrase (“I know it when I;” “know it when I see;” “it when I see it.”). The graph clearly shows the steeply rising and still growing interest in Stewart’s phrase, starting slightly after 1964:
The Ngram search also reveals some interesting instances of similar phrases, both legal and not, pre-dating Jacobellis. Consider two examples: In an obituary for Benjamin Cardozo that ran in the Columbia, Yale and Harvard law journals in 1939, Learned Hand praised Justice Cardozo for his wisdom, writing:
“And what is wisdom — that gift of God which the great prophets of his race exalted? I do not know; like you, I know it when I see it, but I cannot tell of what it is composed.”