The Erie Railway Company v. Pennsylvania was a landmark Supreme Court case that established the doctrine of federal preemption. The case centered around a dispute between the Erie Railway Company and the state of Pennsylvania over the state's attempt to regulate the company's freight rates. The state argued that it had the right to regulate the company's rates, while the company argued that the state's regulations were unconstitutional. The Supreme Court ultimately sided with the company, ruling that the state's regulations were in violation of the Commerce Clause of the Constitution, which grants the federal government exclusive authority to regulate interstate commerce. The Court's decision established the doctrine of federal preemption, which holds that the federal government has the power to preempt state laws that conflict with federal laws. This decision has been cited in numerous cases since then, and has been a cornerstone of federalism in the United States.

In the case of Erie Railway Company v. Pennsylvania, Justice Field delivered a dissenting opinion in which he argued that the state had no right to interfere with interstate commerce and impose regulations on it. He argued that Congress was given exclusive power over interstate commerce by the Constitution and any attempt by states to regulate such activity would be unconstitutional. Furthermore, he noted that if states were allowed to regulate interstate commerce then they could effectively prevent it from occurring altogether, thus violating both the spirit and letter of the Constitution. In conclusion, Justice Field believed that allowing states to interfere with or impede interstate commerce would lead to chaos as each state attempted its own regulation without regard for other jurisdictions or federal law.