Reagan v. Aiken, 1890, was a U.S. Supreme Court case that revolved around the issue of railroad rates in Texas and their regulation by state law. The State of Texas had passed laws regulating freight and passenger tariffs for railroads within its jurisdiction, which were challenged by the railroad companies as unconstitutional because they interfered with interstate commerce. The court ruled in favor of the state's right to regulate these rates under certain conditions - specifically when such regulations do not interfere with interstate commerce or contradict federal legislation on the matter. This decision upheld states' rights to control local industries while also acknowledging federal supremacy over matters involving multiple states or foreign nations.

The dissenting opinion in Reagan v. Aiken argued that the majority's decision to uphold a Texas law regulating railroad freight rates was an overreach of judicial power and violated principles of federalism. The dissenters believed that the state had a right to regulate its own commerce, including setting reasonable rates for services provided by corporations operating within its borders. They contended that it was not the role of the Supreme Court to interfere with this authority unless there was clear evidence that such regulations were unreasonable or discriminatory, which they did not believe existed in this case. Furthermore, they expressed concern about potential negative impacts on businesses if courts could arbitrarily overturn state laws based on their own assessments of reasonableness rather than deferring to legislative judgment.