In Heitler v. United States, the Supreme Court addressed whether a defendant could be convicted of conspiracy to obstruct justice if no actual obstruction occurred. The case involved Samuel Heitler and others who were charged with conspiring to bribe a federal officer in order to prevent the deportation of certain individuals. However, their plan was discovered before any bribery took place or any proceedings were affected. The defendants argued that since there was no actual obstruction of justice, they couldn't be guilty of conspiracy to obstruct it. The Supreme Court disagreed and upheld their convictions. It ruled that an agreement or combination formed for the purpose of obstructing justice is illegal even if it doesn't succeed in its objective - thus affirming that one can conspire to commit an act without actually committing it.

In the dissenting opinion for Heitler v. United States, Justice Holmes argued that the defendant's conviction should be overturned because it was based on evidence obtained through an illegal search and seizure. The majority had upheld the conviction by applying a rule that allowed illegally seized evidence to be used in court if it would have been inevitably discovered anyway. However, Holmes contended this "inevitable discovery" rule was not applicable in this case as there were no facts suggesting such inevitability of lawful discovery independent of unlawful conduct by law enforcement officers. Furthermore, he believed that allowing such evidence undermined Fourth Amendment protections against unreasonable searches and seizures, thereby setting a dangerous precedent for future cases.