Democracies are constrained by strong constitutions from summarily violating the rights of its citizens. Most democracies have due process requirements in place when security services wish to engage in surveillance, search premises, seize evidence, or detain suspects. However, when confronted by serious security challenges, democracies have resorted to authoritarian security measures. Germany, Italy, France, the United Kingdom, and the United States have all adopted aggressive policies to suppress perceived threats to national security.

For example:

In the United States, periodic anti-Communist “Red Scares” occurred when national leaders reacted to the perceived threat of Communist subversion. Government officials reacted by adopting authoritarian measures to end the perceived threats. The first Red Scare occurred after the founding of the Communist Party—USA in 1919, and a series of letter bombs were intercepted. President Woodrow Wilson allowed Attorney General R. Mitchell Palmer to conduct a series of raids—the so-called Palmer Raids—against Communist and other leftist radical groups. Offices of these groups were shut down, leaders were arrested and put on trial, and hundreds were deported.

A second Red Scare occurred in the 1930s. This Scare resulted in the creation of the House Un-American Activities Committee and the passage of the Smith Act in 1940, which made advocacy of the violent overthrow of the government a federal crime. In the late 1940s Communists were prosecuted, and high-profile investigations were made of people such as Alger Hiss.

A third Red Scare occurred in the 1950s when Senator Joseph McCarthy of Wisconsin held a series of hearings to expose Communist infiltration in government, industry, and Hollywood. Hundreds of careers were ruined, and many people were “blacklisted,” meaning that they were barred from obtaining employment.

In Northern Ireland, the British government has periodically passed legislation to combat terrorism by the IRA. These laws granted British forces authoritarian powers in Northern Ireland. One such law was the 1973 Northern Ireland Emergency Provisions Act, which provided the military with sweeping powers to temporarily arrest and detain people and to search homes in Northern Ireland without warrants. Under the Act, the army detained hundreds of people and searched more than 250,000 homes. This sweep was actually fairly successful, because thousands of weapons were found and seized.