In the case of Keck v. United States in 1898, the U.S Supreme Court ruled on a matter involving mail fraud. The defendant, Mr. Keck, was accused of using the postal service to defraud individuals by selling counterfeit silver dollars and misrepresenting them as genuine coins from an old Spanish shipwreck. He contested his conviction arguing that he had not committed any fraudulent acts because he did not personally send or receive any letters related to this scheme; rather it was done through agents who were unaware of his intentions. The court rejected this argument stating that if one uses the postal system with intent to deceive or defraud others, they are liable for their actions regardless if they themselves physically mailed anything or received anything via post directly linked to their fraudulent activities. This ruling clarified that indirect use of mails can still constitute mail fraud under federal law.

In the dissenting opinion for Keck v. United States, the justice argued that the majority's decision to uphold Keck's conviction was incorrect because it failed to consider important aspects of his case. The justice believed that there were significant issues with how evidence was obtained and used against Keck during his trial. They felt that these issues violated his constitutional rights, particularly those related to due process and protection from unreasonable searches and seizures. Furthermore, they disagreed with the majority’s interpretation of what constituted a lottery under federal law at that time; in their view, not all games involving chance should be classified as such. This disagreement extended into concerns about potential overreach by federal authorities in enforcing anti-lottery laws on activities traditionally regulated by states themselves.