In the case of Taylor v. United States in 1907, the Supreme Court ruled on a matter involving interstate commerce and criminal law. The defendant, Taylor, was charged with illegally transporting women across state lines for "immoral purposes" under the Mann Act (also known as White-Slave Traffic Act). He challenged his conviction arguing that he had not been proven guilty beyond reasonable doubt because there was insufficient evidence to show that he intended to violate the act when he transported two women from Missouri to Kansas City. However, Justice Oliver Wendell Holmes Jr., writing for a unanimous court, rejected this argument stating that it is not necessary to prove intent if it can be shown that an individual knowingly committed an act which violates federal law. Therefore, since Taylor knew he was transporting these women across state lines and engaged in immoral activities with them afterwards - regardless of whether or not he specifically intended to break the Mann Act - his actions were deemed illegal by virtue of violating federal law.

In the dissenting opinion for Taylor v. United States, Justice Harlan argued that the majority's decision to uphold a federal law prohibiting interstate transportation of women for "immoral purposes" was an overreach of Congressional power under the Commerce Clause. He contended that this law did not regulate commerce per se but rather sought to impose moral standards and punish immoral conduct, which he believed fell within states' police powers rather than federal jurisdiction. Harlan warned against expanding federal authority into areas traditionally reserved for state control, cautioning it could erode states' rights and upset the balance of power in our federal system.