To check the expression of opinions that we loathe and believe to be fraught with death?

[Anthony Lewis, the former New York Times columnist] wrote that there was “genuinely dangerous” speech that did not meet the imminence requirement [of what was considered outside the realm of First Amendment protection.]

“I think we should be able to punish speech that urges terrorist violence to an audience, some of whose members are ready to act on the urging,” Mr. Lewis wrote. “That is imminence enough.”

Harvey A. Silverglate, a civil liberties lawyer in Cambridge, Mass., disagreed. “When times are tough,” he said, “there seems to be a tendency to say there is too much freedom.”

“Free speech matters because it works,” Mr. Silverglate continued. Scrutiny and debate are more effective ways of combating hate speech than censorship, he said, and all the more so in the post-Sept. 11 era.

“The world didn’t suffer because too many people read ‘Mein Kampf,’ ” Mr. Silverglate said. “Sending Hitler on a speaking tour of the United States would have been quite a good idea.”

Mr. Silverglate seemed to be echoing the words of Justice Oliver Wendell Holmes Jr., whose 1919 dissent in Abrams v. United States eventually formed the basis for modern First Amendment law.

“The best test of truth is the power of the thought to get itself accepted in the competition of the market,” Justice Holmes wrote.

“I think that we should be eternally vigilant,” he added, “against attempts to check the expression of opinions that we loathe and believe to be fraught with death.”

American Exception: Unlike Others, U.S. Defends Freedom to Offend in Speech (New York Times, 12 June 2008)