Final answer:
The Sedition Act of 1918 was opposed because it restricted freedom of speech and made it illegal to criticize the government or the war effort.
Step-by-step explanation:
The Sedition Act of 1918 was met with opposition primarily because it restricted freedom of speech. This act made it illegal to criticize the government or the war effort, resulting in the prosecution of approximately two thousand people. Many individuals, such as socialist leader Eugene V. Debs, were imprisoned for expressing anti-war sentiments. The Sedition Act violated the First Amendment of the U.S. Constitution, which protects the right to free speech.