In the Norfolk & Western Railway Co. v. Hiles case of 1995, the U.S Supreme Court ruled in favor of Norfolk & Western Railway Co., overturning a decision by Illinois courts that had awarded damages to Robert Hiles for injuries sustained during his work at the railway company. The central issue was whether federal law preempted state law on safety standards related to coupling devices on trains, which were implicated in Hiles' injury. The court held that under the Federal Safety Appliance Act (FSAA), states could not impose additional liability rules beyond those established federally for automatic couplers on railroad cars. It concluded that allowing such state-level regulations would undermine uniform national regulation and potentially burden interstate commerce.

In the dissenting opinion for Norfolk & Western Railway Co. v. Hiles, Justice Thomas disagreed with the majority's interpretation of federal law preempting state law in regards to train brake safety standards. He argued that Congress intended a balance between uniform national safety regulations and states' ability to impose additional requirements when necessary for local safety concerns. The Federal Railroad Safety Act (FRSA) does not expressly prohibit states from imposing their own laws regarding train brakes unless those laws are incompatible with federal regulations or cover an area already regulated by federal law, according to his interpretation. In this case, he believed Illinois’ requirement for two braking systems did not conflict with any specific provision in FRSA nor was it less stringent than existing federal rules; hence it should be allowed under state police powers reserved by the Tenth Amendment.