In the case of Roach, Secretary of State of Missouri v. Atchison, Topeka and Santa Fe Railway Company (1909), the U.S Supreme Court was tasked with determining whether a state could impose taxes on interstate commerce companies operating within its borders. The dispute arose when Missouri's Secretary of State attempted to levy taxes against Atchison, Topeka and Santa Fe Railway Company for conducting business in the state. The railway company argued that as an interstate commerce entity, it should be exempt from such taxation under federal law. In its decision, the court sided with the railway company stating that states cannot tax entities involved in interstate commerce because this power is reserved exclusively for Congress under Article I Section 8 Clause 3 (the Commerce Clause) of the Constitution. This ruling reinforced federal supremacy over states regarding regulation and taxation of interstate commerce.

The dissenting opinion in the case of Roach v. Atchison, Topeka and Santa Fe Railway Company argued that the majority's decision to uphold a Missouri law requiring railroads to provide separate coaches for black and white passengers was incorrect. The dissenters believed this law violated the Fourteenth Amendment’s Equal Protection Clause, which guarantees all citizens equal protection under the law. They contended that segregation inherently implied inequality because it suggested one race was unfit to share public facilities with another. Furthermore, they pointed out inconsistencies in how such laws were applied; for example, no similar provisions existed for other forms of transportation like streetcars or steamboats within state borders. This inconsistency indicated an arbitrary application of supposed 'separate but equal' policies rather than genuine concern for maintaining peace between races as claimed by proponents of segregation laws.