In Mandoli v. Acheson, Secretary of State (1952), the U.S Supreme Court ruled on a case involving an Italian immigrant named Luigi Antonio Mandoli who had been living in the United States since 1913 but was never naturalized as a citizen. During World War II, he returned to Italy and served in its army for two years before returning to America after the war ended. The US government argued that by serving in Italy's military during wartime, Mandoli had forfeited his right to permanent residency under Section 401(g) of the Nationality Act of 1940 which states that any alien who leaves or remains outside the country during times of war with intent to evade military service loses their status as a lawful resident. The court disagreed with this interpretation and held that there was no evidence showing Mr. Mandoli left America intending to avoid being drafted into its armed forces; rather it seemed he went back because his mother was ill and remained due to circumstances beyond his control - namely, WWII breaking out soon after he arrived there making return impossible until hostilities ceased.

In the dissenting opinion for Mandoli v. Acheson, it was argued that the majority's decision to strip Mr. Mandoli of his American citizenship due to his service in the Italian army during World War II was unjust and inconsistent with previous rulings on similar cases. The dissenting justices believed that serving in a foreign military did not necessarily equate to voluntarily renouncing one's U.S. citizenship, especially considering Mr. Mandoli had been forced into service by Italy while residing there temporarily and had made efforts to return home as soon as possible after being discharged from duty. They also pointed out that he never swore allegiance or loyalty oath to Italy nor did he ever formally renounce his U.S nationality before any competent authority which are usually required for expatriation under international law standards.