In the Hancock v. Louisville & Nashville Railroad Company case of 1891, the U.S Supreme Court ruled in favor of the railroad company. The dispute arose when a train owned by Louisville & Nashville Railroad Company collided with a wagon driven by Mr. Hancock at an unguarded crossing, resulting in his death. His widow filed a lawsuit against the company for negligence and was awarded damages by lower courts based on Alabama state law which held railroads liable for accidents at crossings unless they could prove no negligence on their part. However, upon appeal to the Supreme Court, it was determined that this state law conflicted with federal commerce laws as it interfered with interstate commerce operations and placed undue burdens on them without sufficient public benefit or safety justification. Therefore, while acknowledging that states have power to regulate local matters affecting public safety such as railroad crossings within their jurisdiction under police powers doctrine; these regulations must not conflict with federal laws or unduly burden interstate commerce. The court concluded that Alabama's strict liability rule did both and hence was unconstitutional under Supremacy Clause and Commerce Clause of US Constitution respectively; reversing previous judgments against Louisville & Nashville Railroad Company.

In the dissenting opinion for Hancock v. Louisville & Nashville Railroad Company, Justice Lamar disagreed with the majority's decision to uphold a Kentucky statute that allowed state courts to assign damages in cases where railroads were found guilty of charging unreasonable rates. He argued that this law violated the Fourteenth Amendment by depriving railroad companies of their property without due process of law. According to him, it was not fair or constitutional for a court to determine what constituted an "unreasonable" rate and then penalize companies based on this subjective judgment. Instead, he believed that such decisions should be left up to regulatory bodies specifically tasked with overseeing industries like railroads. Furthermore, he contended that allowing individual states too much power over interstate commerce could lead to inconsistent regulations and disrupt national economic stability.