In the 1919 case of O'Connell et al. v. United States, the U.S Supreme Court ruled on a matter involving conspiracy to obstruct justice and perjury. The defendants were charged with conspiring to prevent testimony in a federal court by bribing potential witnesses not to testify against them in an ongoing trial related to mail fraud charges. They were also accused of committing perjury during their own testimonies at this trial. The Supreme Court upheld the convictions for both obstruction of justice and perjury, stating that it was within Congress's power under Article I Section 8 Clause 18 (the Necessary and Proper Clause) of the Constitution, which allows Congress "to make all Laws which shall be necessary and proper" for executing its powers, to enact laws punishing such actions as they interfere with judicial proceedings. This ruling affirmed that attempts or conspiracies aimed at preventing witness testimonies through bribery are punishable offenses under federal law because they undermine the integrity of legal proceedings.

In the dissenting opinion for O'Connell et al. v. United States, Justice Oliver Wendell Holmes Jr., joined by Justice Louis D. Brandeis, argued that the defendants' convictions should be overturned because their actions did not present a "clear and present danger" to the United States government's war effort during World War I. The defendants were convicted under the Espionage Act of 1917 for distributing leaflets urging resistance to the draft. However, Holmes contended that such speech was protected by First Amendment rights unless it posed an immediate threat to national security or public safety - a standard he had previously articulated in Schenck v. United States (1919). He believed that this case failed to meet those criteria as there was no evidence showing direct harm caused by these leaflets; thus, punishing them would infringe upon their constitutional right of free speech.