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On “I Know It When I See It,” 105 Yale Law Journal 1023 (1996)


My subject is one of the most famous phrases in the entire history of Supreme Court opinions: "I know it when I see it." The phrase appears in Justice Potter Stewart's concurring opinion in Jacobellis v. Ohio, a pornography case decided by the Court in 1964. Although many people have appropriated the phrase—some approvingly, some not—no one has ever examined it in any way commensurate with its fame. But the phrase repays reflection. Aside from its provocative place in the history of pornography regulation, "I know it when I see it" invites us to reappraise the role of nonrational elements in judicial decisionmaking, which I think deserve both more attention and more acceptance than they typically enjoy. Such a reappraisal is my underlying purpose here.

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