U.S. citizens, as members of a nation which originally defined itself as protecting the individual from the State and guaranteeing the right to dissent, are particularly committed to safeguarding freedom of expression. In this article, based on the observation and the study of that society, the author examines whether, when « national security » is seen to be in jeopardy, the practice regarding civil liberties changes radically. She concludes that this society always struggles with its own contradictions insofar as a large number of groups, some of them highly organized and with a political agenda, are intent not only on expressing « their » own truths, but on forcing them on other citizens, thereby preventing others from learning and practising intellectual debate.