In the 1933 case of Hamburg-American Line v. United States, the Supreme Court upheld a ruling that allowed for fines to be imposed on shipping companies who brought non-citizen passengers into the U.S., even if those individuals were later deemed admissible by immigration authorities. The Hamburg-American Line had been fined $1,000 per passenger for two German nationals they transported to New York in 1929 without proper documentation. Although both Germans were eventually granted entry into America after an appeal process, the company was still held liable for their initial illegal entry under Section 16 of Immigration Act of February 5th, 1917 which stipulates penalties against transportation lines bringing ineligible aliens into US territory. The court ruled that this law was not intended as punishment but rather as a regulatory measure to discourage unlawful immigration and thus it did not violate due process rights or constitute double jeopardy.

The dissenting opinion in the case of Hamburg-American Line v. United States argued that the majority's interpretation of the Espionage Act was overly broad and potentially unconstitutional. The dissenters contended that, under this interpretation, any person who provided assistance to a foreign ship could be found guilty of aiding an enemy during wartime, even if they had no knowledge or intent of furthering hostile actions against the U.S. They believed this would lead to unjust prosecutions and infringe upon individual rights. Furthermore, they disagreed with applying conspiracy charges for acts committed abroad by non-U.S citizens which were not directly aimed at harming American interests. They felt such application stretched beyond reasonable jurisdictional boundaries and violated principles of international law.