WIST

Censorship reflects a society’s lack of confidence in itself.

Justice Potter Stewart (1915-1985) US Supreme Court (1959-81)
(Attributed)

The Fourth Amendment, and the personal rights which it secures, have a long history. At the very core stands the right of a man to retreat into his own home and there be free from unreasonable governmental intrusion.

Justice Potter Stewart (1915-1985) US Supreme Court (1959-81)
Silverman v. United States, 365 U.S. 505, unanimous opinion (6 Mar 1961)
Full ruling. Note that the quote is frequently misidentified as being from Katz v. United States or Bartkus v. Illiinois.

I have reached the conclusion, which I think is confirmed at least by negative implication in the Court’s decisions since Roth and Alberts, that under the First and Fourteenth Amendments criminal laws in this area are constitutionally limited to hard-core pornography. 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.

Justice Potter Stewart (1915-1985) US Supreme Court (1959-81)
Concurring opinion, Jacobellis v. Ohio, 378 U.S. 184 (1964)

Source of the paraphrase, "I can't define obscenity/pornography, but I know it when I see it." Full text.

May the state fence in the harmless mentally ill solely to save its citizens from exposure to those whose ways are different? One might as well ask if the state, to avoid public unease, could incarcerate all who are physically unattractive or socially eccentric. Mere public intolerance or animosity cannot constitutionally justify the deprivation of a person’s physical liberty.

Justice Potter Stewart (1915-1985) US Supreme Court (1959-81)
Unanimous opinion, O’Connor v. Donaldson, 422 U.S. 563 (1975)
Full opinion.