Complex sentence: The relevant Supreme Court precedent is Schenck v. United States, 1919, opholding the espionage conviction of Charles Schenck for distributing ant-draft leaflets to potential draftees.
Split into simpler sentences: The relevant Supreme Court precedent is Schenck v. United States. During World War I, Charles Schenck had been convicted of espionage for distributing ant-draft leaflets to potential draftees.