In the case of United States v. Nardello et al., 1968, the U.S Supreme Court was tasked with determining whether or not "extortion" as defined by Pennsylvania law fell under the federal Travel Act's definition of "unlawful activity." The defendants, Joseph and Elizabeth Nardello, were convicted for violating this act after they traveled from Pennsylvania to New Jersey to collect an unlawful debt through extortionate means. However, their conviction was overturned on appeal due to a perceived discrepancy between state and federal definitions of extortion. Upon review, the Supreme Court held that while there may be differences in how states define specific crimes like extortion, what mattered more for purposes of applying federal law (in this case the Travel Act) was whether or not those actions would generally be considered illegal across jurisdictions. Therefore it reinstated their convictions stating that even though each state might have different laws regarding certain activities such as gambling or liquor violations; if these activities are deemed illegal then they fall within purview of 'unlawful' under Federal Law.

In the dissenting opinion for United States v. Nardello et al., Justice Harlan disagreed with the majority's interpretation of "racketeering" under federal law, arguing that it was too broad and could potentially criminalize innocent behavior. He contended that Congress intended to target only those who engage in organized crime activities when they enacted the Travel Act, not individuals involved in isolated or sporadic illegal acts. According to him, a narrower definition of racketeering would better align with Congressional intent and prevent potential misuse of this legislation against ordinary citizens engaged in minor offenses. Furthermore, he expressed concern about possible violations of due process rights if such an expansive interpretation were allowed to stand.