In Heflin v. United States, the defendant was convicted of both robbing a post office and possessing stolen money from the same robbery. The Supreme Court ruled that he could not be punished for both crimes as they were part of the same offense under federal law. The court found that Congress had intended to punish thefts from post offices separately from possession of stolen property, but did not intend to allow cumulative punishments in cases where an individual stole money and then possessed it afterward. Therefore, Heflin's conviction for possession was overturned because it constituted double jeopardy - being tried twice for substantially the same crime.

In the dissenting opinion for Heflin v. United States, Justice Harlan argued that the majority's interpretation of Congress' intent was incorrect. He believed that Congress intended to punish each distinct harmful act separately, even if those acts were part of a single criminal episode. Therefore, he disagreed with the majority's view that robbing a bank and possessing stolen money from said robbery should be considered as one offense rather than two separate offenses under federal law. In his view, this misinterpretation could potentially lead to lenient sentences for criminals who commit multiple crimes in quick succession or simultaneously during one event. This would undermine the purpose of having different statutes addressing different aspects of criminal behavior.