Alan R. Novak began clerking for Supreme Court Justice Potter Stewart in 1963, the same year he graduated from the Yale Law School. As luck would it for Novak, the Supreme Court was in the midst of considering what would prove to be a landmark case, that of Jacobellis v. Ohio. It seemed Nico Jacobellis, the manager of an art theatre in Cleveland Heights, had decided to offer a screening of the French film Les Amants. French films being what French films are, little was left to the imagination. As a result, the state of Ohio, which apparently placed an inordinate value on the ability to exercise one's imagination, declared the film unsuitable for the tony citizens of Cleveland Heights. Jacobellis was fined $2,500 and appealed, losing all the way to the Supreme Court. We'll let Novak tell the rest of the story…

"After several days reviewing with the other court members the materials related to the '63 Term pornographic materials, Justice Stewart came to the office for a Saturday stint of opinion writing. I was there alone when he arrived, and we visited together to discuss his reaction to the case. . . . I had been a Marines officer; he a Navy officer. We discussed our experiences with material we had seen during our military careers, and discovered we had both seen materials we considered at the time to be pornographic, but this conclusion was arrived at somewhat intuitively. We agreed that 'we know it when we see it,'…" ("The Origins of Justice Stewart's 'I Know It When I See It,'" Wall Street Journal Law Blog, September 27, 2007)

The phrase "I know it when I see it" thus became part of the American lexicon, not merely because of its eloquent simplicity, but for the very fact that, while admitting certain expressions can be deemed "obscene" (and thus outlawed), the majority could not agree on what constituted an obscenity.