In the case of Missouri Pacific Railroad Company v. Hanna in 1924, the U.S Supreme Court ruled on a dispute involving an employee's injury claim against his employer under federal law. The plaintiff, Mr. Hanna was injured while working for Missouri Pacific Railroad and sought compensation under the Federal Employers' Liability Act (FELA). The railroad company argued that since he was not engaged in interstate commerce at the time of his injury, FELA did not apply to him. However, Hanna claimed that because some part of his work involved interstate commerce activities, he should be covered by FELA regardless of what specific task he was performing when injured. The Supreme Court sided with Mr.Hanna stating that if an employee is generally employed in tasks related to interstate commerce - even if they are not specifically engaged in such tasks at every moment - then they are considered as being "employed" in such work for purposes of FELA coverage. Therefore it held that employees like Mr.Hanna who were regularly assigned duties connected with interstate transportation could recover damages for injuries sustained during any part their employment.

In the dissenting opinion for Missouri Pacific Railroad Company v. Hanna, Justice Holmes argued that the court should not have overturned a decision by the Arkansas Supreme Court regarding an injury claim made by a railroad worker against his employer under federal law. He believed that it was inappropriate for the U.S. Supreme Court to intervene in this case because there were no constitutional issues at stake and state courts are competent to interpret federal laws when they apply within their jurisdiction. Furthermore, he contended that even if there had been an error in applying federal law, it would not necessarily mean that state courts had overstepped their bounds or violated any rights of litigants before them; rather, such errors could be corrected through ordinary appellate procedures without resorting to extraordinary intervention from higher courts.