In St. John v. Erie Railway Company, the Supreme Court of the United States was asked to decide whether a state court had the authority to enjoin a railroad company from operating its trains on a certain day of the week. The plaintiff, St. John, had obtained an injunction from the state court prohibiting the railroad company from operating its trains on Sundays. The railroad company argued that the state court did not have the authority to issue such an injunction, as it was in violation of the Commerce Clause of the United States Constitution. The Supreme Court held that the state court did not have the authority to issue the injunction. The Court reasoned that the Commerce Clause of the Constitution gave Congress exclusive power to regulate interstate commerce, and that the state court's injunction was in direct conflict with Congress' power. The Court further held that the state court's injunction was an unconstitutional interference with interstate commerce. The Court's decision in St. John v. Erie Railway Company established that state courts do not have the authority to interfere with interstate commerce. This decision has been cited in numerous cases since then, and has been used to support the principle that Congress has exclusive power to regulate interstate commerce.

Justice Field delivered the dissenting opinion in St. John v. Erie Railway Company, arguing that the majority had failed to consider a key point of law in their decision: whether or not an individual can be held liable for damages caused by another person's negligence while operating a vehicle owned by them. The plaintiff argued that he was entitled to recover from the defendant railway company because it had employed and entrusted its locomotive engine to an incompetent engineer who negligently operated it, causing injury and damage to his property. Justice Field disagreed with this argument on two grounds: firstly, he argued that there was no evidence presented at trial which showed any fault on behalf of the railroad company; secondly, even if such evidence did exist, liability could only be established if it were proven beyond reasonable doubt that they knew or should have known about the incompetence of their employee prior to entrusting him with control over their locomotive engine. In conclusion, Justice Field believed that since neither condition had been met in this case then no legal basis existed for holding either party responsible for damages incurred as a result of negligent operation of said locomotive engine.