The priceless heritage of our society is the unrestricted constitutional right of each member to think as he will. Thought control is a copyright of totalitarianism, and we have no claim to it. It is not the function of the government to keep the citizen from falling into error; it is the function of the citizen to keep the government from falling into error. We could justify any censorship only when the censors are better shielded against error than the censored.

American Communications Association v. Douds, 339 U.S. 382, 442-43 (1950) - Judicial opinions