In the case of United States v. Falcone et al., 1940, the Supreme Court ruled that individuals who supplied ingredients to illegal distilleries were not guilty of conspiracy to violate federal prohibition laws unless they had knowledge that their customers intended to use these supplies for unlawful purposes. The defendants in this case were suppliers of sugar and yeast, which are commonly used in the production of alcohol but also have legitimate uses. The court held that while it was clear these suppliers knew their products could be used illegally, there was no evidence proving they knew or intended them specifically for such use by their clients. Therefore, mere association with known criminals or selling goods knowing they may potentially be put towards illegal activities did not constitute a violation under federal law.

In the dissenting opinion for United States v. Falcone et al., Justice Frank Murphy argued that the majority's interpretation of conspiracy law was too narrow and failed to consider the broader implications of organized crime. He believed that those who knowingly supplied illegal distilleries with necessary materials were just as guilty in contributing to a criminal enterprise as those directly involved in producing alcohol illegally. According to him, these suppliers should be considered co-conspirators because their actions facilitated and perpetuated illicit activities, even if they did not actively participate in them. This view contrasts sharply with the majority's ruling which held that merely selling goods knowing they will be used unlawfully does not make one part of a conspiracy unless there is an agreement between seller and buyer about unlawful use.