In Costello v. United States, the Supreme Court ruled in favor of Frank Costello, a reputed gangster who was facing deportation due to his criminal history. The case centered around whether or not the government could use evidence from an earlier trial that had been dismissed on technical grounds as part of their argument for deportation. The court found that this would violate double jeopardy laws and therefore could not be used against him in immigration proceedings. This decision set a precedent for how evidence can be used in immigration cases and reinforced protections against double jeopardy.

In the dissenting opinion for Costello v. United States, Justice Felix Frankfurter argued that the majority's decision to allow denaturalization based on a lack of "good moral character" during the statutory period was an overreach of judicial power. He contended that this interpretation went beyond what Congress had intended when it enacted the relevant immigration and naturalization laws. Furthermore, he asserted that such a broad interpretation could potentially lead to abuses of power and arbitrary decisions about who is considered morally fit for citizenship. He also expressed concern about using allegations from before the statutory period as evidence against someone's current moral character, arguing it violated principles of fairness and due process.