The way the United States handled civil liberties during WWI constitutes one of the more regrettable moments in American History. In an atmosphere of uncertainty caused by the rise of anarchist movements in both Europe and in the United States, the government cracked down on dissent in all its forms. The passage of the Espionage and Sedition Acts in 1917 made it illegal to question or criticize the government or to oppose the governments position regarding entrance into WWI, including opposition to compulsory service in the military through the draft.
Under the acts many people were imprisoned or deported for opposing US entrance into the war. These people felt the war was being fought to protect the financial interests of the rich and not to protect democracy in Europe as the government claimed. The fact that the government was severely limiting democracy at home through the Acts gave credence to these claims.
Emma Goldman was a well-known opponent of the war and she spoke passionately against US involvement. She was arrested and deported for exercising her First Amendment Rights.
Eugene Debs was a Socialist candidate for the Presidency and was arrested and sentenced to prison for making an anti-draft speech in Dayton Ohio. While in prison he received nearly a million votes for President.
Attorney General Mitchell Palmer organized a series of raids to arrest, deport, or imprison radicals who opposed the US war effort. Hundreds of people were tried and convicted in America's first "Red Scare."
The Supreme Court did little to stop the erosion of these First Amendment Rights. In the famous Schenck vs United States case of 1919, even liberal judges supported the right of the government to limit free speech if it could assert that the speech created a clear and present danger to the country. A man who was handing out leaflets opposing the draft was convicted of creating such a "clear and present danger."
Most of the limits brought on by the Espionage and Sedition Acts have eroded over time, but in the time of war the government still has broad power to limit civil liberties if it feels its war efforts are being criticized.