Once a government is committed to the principle of silencing the voice of opposition, it has only one way to go, and that is down the path of increasingly repressive measures, until it becomes a source of terror to all its citizens and creates a country where everyone lives in fear. We must, therefore, be on our guard against extremists who urge us to adopt police state measures. (Harry S. Truman, Special Message to the Congress on the Internal Security of the United States, August 8, 1950)