In the case of United States v. O'Donnell et al., 1937, the Supreme Court ruled on whether or not a federal law prohibiting conspiracy to defraud the U.S. government was applicable in cases where no financial loss occurred to the government as a result of said conspiracy. The defendants were charged with conspiring to violate Prohibition laws and subsequently convicted under Section 37 of the Criminal Code for conspiring to defraud the United States by obstructing its lawful governmental functions. They appealed their convictions arguing that since there was no monetary loss involved, they could not be found guilty under this statute. However, in a unanimous decision delivered by Justice Benjamin N Cardozo, it was held that an attempt to interfere with or obstruct one of these functions is itself an offense against the U.S., even if there's no direct financial harm caused by such interference or obstruction. Therefore, despite causing no actual pecuniary loss to any department of Government nor depriving it of property rights; impeding its lawful activities still constituted fraud within meaning and purpose behind Section 37.

In the dissenting opinion for United States v. O'Donnell et al., Justice McReynolds argued that the majority's decision to uphold convictions under a federal mail fraud statute was an overreach of federal power. He contended that the defendants' actions, while morally reprehensible, did not constitute a violation of this specific law as it was intended to prevent misuse of postal services rather than regulate morality or business practices. Furthermore, he expressed concern about potential abuse and arbitrary enforcement if such broad interpretations were allowed to stand. In his view, allowing these convictions would set a dangerous precedent by expanding federal jurisdiction into areas traditionally governed by state law and potentially criminalizing ordinary business transactions based on subjective judgments about their fairness or honesty.