In the United States Supreme Court case of The United States v. John Rose and George Kinlock, the appellants were charged with violating a federal law that prohibited trading in slaves between states. The defendants argued that they had not violated this law because their actions occurred before it was passed by Congress. However, the court found that even though their actions took place prior to passage of the statute, they still constituted a violation since Congress had already declared slavery illegal within its jurisdiction at the time of those acts. Furthermore, as citizens subject to federal laws, Rose and Kinlock could be held liable for any violations regardless of when those acts occurred or whether there was an existing statute prohibiting them at that time. Ultimately, this ruling established precedent for holding individuals accountable under federal statutes even if their conduct preceded enactment of such laws.

In the case of United States v. Rose and Kinlock, the Supreme Court was asked to decide whether a federal statute that prohibited any person from carrying on trade or commerce with Native Americans without a license applied to two individuals who had purchased goods from an Indian tribe in exchange for money. The majority opinion held that it did apply, but Justice Curtis dissented. He argued that since Congress had not explicitly stated its intention to include such transactions within the scope of the law, then they should be excluded as beyond its reach. Furthermore, he noted that this interpretation would lead to absurd results if extended too far; for example, it could potentially criminalize innocent acts like giving presents or gifts between Indians and non-Indians. In conclusion, Justice Curtis believed there were limits on what Congress could regulate under this particular statute and urged his colleagues not to extend those limits further than necessary in order to avoid unintended consequences.