Final answer:
The U.S. government has violated civil liberties during times of national security risk, notably during World War I with the Espionage and Sedition Acts and after 9/11 with the USA PATRIOT Act.
Step-by-step explanation:
The civil liberties of citizens were violated by the U.S. government during various moments when national security was deemed at risk. Notable examples include the World War I era, marked by the Espionage and Sedition Acts which allowed the government to silence dissent, and the post-9/11 period when the USA PATRIOT Act expanded government powers in matters such as surveillance.
The establishment of the American Civil Liberties Union (ACLU) in 1920 aimed to protect civil liberties, showing that throughout U.S. history, there has been a tension between security and freedom. Civil liberties can be impaired in times of crisis, and understanding the balance between individual rights and communal safety is a recurring concern.