In Haupt v. United States (1946), the U.S. Supreme Court upheld the conviction of Hans Max Haupt, a German-born naturalized American citizen who was found guilty of treason for aiding his son, Herbert Haupt, an enemy saboteur during World War II. The court ruled that even though Hans Max Haupt had shown no disloyalty to America through overt acts and claimed he acted under duress fearing for his family's safety in Germany if he did not assist his son; these were insufficient defenses against charges of treason. The court emphasized that every person owes allegiance to the country where they reside and enjoy protection from its laws regardless of their citizenship status or personal circumstances. Therefore, any act knowingly committed with intent to betray that country constitutes treason as defined by Article III Section 3 Clause 1 of the Constitution.

In the dissenting opinion for Haupt v. United States, Justice Murphy argued that Haupt's conviction should be overturned because there was insufficient evidence to prove his guilt beyond a reasonable doubt. He contended that the government failed to provide concrete proof of Haupt’s intent and knowledge in aiding an enemy during wartime, which is essential under treason law. The majority relied heavily on circumstantial evidence and assumptions about familial relationships rather than direct evidence of treasonous activity or intent. Furthermore, he pointed out inconsistencies in witness testimonies used against Haupt and criticized the use of prejudicial statements made by prosecution during trial proceedings as they could have influenced jury decision-making unfairly. Thus, Murphy believed that due process had been compromised in this case.