The U.S. Supreme Court case Chicago, Rock Island & Pacific Railway Company et al. v. Ward in 1919 revolved around the issue of whether a state could regulate rates for intrastate transportation on interstate railroads without violating the Commerce Clause of the Constitution. The plaintiff, a railway company operating across several states, argued that Oklahoma's regulation interfered with its ability to conduct business and was therefore unconstitutional under federal law governing interstate commerce. However, the court ruled against this argument stating that while Congress has exclusive authority over interstate commerce, it does not prevent states from regulating aspects of such commerce within their borders as long as they do not conflict with federal laws or impede free flow of trade among states. In this particular case, Oklahoma's rate-setting did not interfere with any existing federal regulations nor obstruct national uniformity in railroad operations; hence it was deemed constitutional by the court.

In the dissenting opinion for Chicago, Rock Island & Pacific Railway Company et al. v. Ward (1919), Justice Oliver Wendell Holmes Jr., joined by Justice Louis Brandeis, disagreed with the majority's ruling that a state could not regulate railroad rates in interstate commerce without violating the Commerce Clause of the U.S Constitution. They argued that states should have some power to regulate such matters when Congress has not acted on them and where there is no conflict with federal law or policy. The dissenters believed that this case did not present any such conflict and therefore Oklahoma’s regulation was valid under its police powers to protect public health and safety, as well as promote general welfare within its borders.