In Debs v. United States (1918), the U.S Supreme Court upheld the conviction of Eugene V. Debs for violating the Espionage Act of 1917, which made it a crime to interfere with military recruitment or operations during World War I. Debs, a prominent socialist leader and five-time presidential candidate, had given an anti-war speech in Canton, Ohio that criticized American involvement in WWI and encouraged resistance to the draft. He was subsequently arrested and convicted under this act on grounds that his words could incite insubordination within military ranks and obstruct recruitment efforts. The defense argued that his First Amendment rights were violated as he merely expressed his personal opinion without any intent to obstruct recruiting or enlistment service; however, these arguments were rejected by Justice Oliver Wendell Holmes Jr., who delivered the unanimous decision of court stating that while free speech is protected under First Amendment but not when it poses "a clear and present danger" to national security interests - establishing what became known as 'clear-and-present-danger test' for determining when government may restrict free speech.

In the dissenting opinion for Debs v. United States, Justice Oliver Wendell Holmes Jr. argued that Eugene V. Debs' conviction under the Espionage Act of 1917 was a violation of his First Amendment rights to free speech and expression. He contended that Debs’ anti-war speech did not pose a "clear and present danger" to national security or military recruitment efforts during World War I, which should be the standard used in determining whether such expressions are protected by the Constitution or punishable as crimes against state interests. Holmes believed that unless words directly incite immediate harm or illegal action, they should not be subject to criminal prosecution; otherwise it would infringe upon individual liberties guaranteed by the Bill of Rights.