In the case of Seaboard Air Line Railway v. Florida ex rel Ellis, Attorney General in 1906, the U.S Supreme Court ruled on a dispute between a railway company and the state of Florida. The State had passed legislation that required railroads to provide equal facilities for both white and black passengers within its jurisdiction. However, Seaboard Air Line Railway argued that this law was unconstitutional as it interfered with interstate commerce which is under federal control according to Article I Section 8 Clause 3 of the Constitution (the Commerce Clause). The court sided with Florida ruling that while Congress has power over interstate commerce, states also have authority to regulate local matters affecting public health or safety unless they directly conflict with federal laws or regulations. Therefore, requiring separate but equal accommodations did not violate any constitutional provisions.

In the dissenting opinion for Seaboard Air Line Railway v. Florida Ex Rel Ellis, Attorney General, Justice Harlan disagreed with the majority's decision that a state law requiring railroads to provide equal facilities for white and black passengers was unconstitutional. He argued that such laws were not an unreasonable burden on interstate commerce as long as they did not interfere with transportation across state lines or impose additional costs on railroad companies. Furthermore, he contended that these laws served a legitimate public interest by preventing racial discrimination and ensuring equal treatment of all citizens regardless of race. Therefore, in his view, states should have the power to regulate local aspects of interstate commerce in order to protect their citizens' rights and welfare.