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. Such persons advocate breaking down the guarantees of the Bill of Rights in order to get at the communists. They forget that if the Bill of Rights were to be broken down, all groups, even the most conservative, would be in danger from the arbitrary power of government.
Harry S. Truman, Special Message to the Congress on the Internal Security of the United States (August 8, 1950)