During WWI, twosocialists, Charles Schenck and Elizabeth Baer handed out fliers in which they stated that the draft was violating the Thirteenth Amendment by obliging citizens to go to war against their will, or in other words, to oblige them to involuntary servitude.
These activitists thought that the First Amendment, which guarantees citizen's rights such as the freedom of speech would protect them. Their case ended up being discussed by the US Supreme Court, which decided that the First Amendment does not confer the right to complain against the war effort or to obstruct the draft.
The range of offences that are considered a crime are stated in the Espionage Act of 1917 and The Sedition Act of 1918, which extended the first.
Holmes was part of the Supreme Court judges who decided in the Schenck case. He introduced the concept of "clear and present danger", that should be tested to determine under which circumstances limits should be placed the First Amendment freedoms: assembly, press and speech.
His position is clear when he tries to implement mechanisms that can circumvent the universal civil rights that all citizens should enjoy according to the Constitution. There should be no limits to those freedoms, as it is the same as not guaranteeing them.
