In Schaefer v. United States (1919), the Supreme Court upheld the conviction of a man who had been found guilty of violating the Espionage Act during World War I. The defendant, Charles Schaefer, was charged with making statements that obstructed recruitment and enlistment services for the military while America was at war. He argued that his First Amendment rights were violated by this charge as he only expressed his personal opinion about conscription being unconstitutional and did not incite any violence or illegal actions against it. However, in its decision, the court ruled that under wartime conditions certain expressions could be restricted if they posed a clear danger to national security interests - even if those expressions didn't directly incite unlawful action.

In the dissenting opinion for Schaefer v. United States, Justice Louis Brandeis argued that the defendants' convictions should be overturned because their actions did not constitute a clear and present danger to the nation's security during World War I. He believed that they were merely expressing their political beliefs about military conscription, which is protected by free speech under the First Amendment of U.S Constitution. Furthermore, he contended that there was no evidence presented at trial showing an immediate threat or harm caused by these expressions of belief. Therefore, in his view, punishing such acts would infringe upon citizens' constitutional rights to freedom of expression and assembly without sufficient justification from government authorities.