In the 1906 case of American Express Company of New York v. Kentucky, the U.S. Supreme Court ruled in favor of Kentucky, upholding a state law that required out-of-state corporations to pay taxes on their gross receipts from business conducted within the state. The court found that this did not violate the Commerce Clause or Due Process Clause of the Constitution as argued by American Express Company (AmEx). AmEx had contended that it was being unfairly taxed because its operations were interstate commerce and thus should be exempt from such taxation under federal law. However, Justice Oliver Wendell Holmes Jr., writing for a unanimous court, stated that while states cannot tax goods moving through interstate commerce directly, they can impose indirect taxes so long as they do not discriminate against or unduly burden interstate commerce.

The dissenting opinion in the case of American Express Company of New York v. Kentucky argued that the state's taxation on the company was unconstitutional. The justice contended that it violated both due process and equal protection clauses under the Fourteenth Amendment, as well as infringed upon interstate commerce regulations. He believed that this tax burden placed on express companies operating across state lines was discriminatory and excessive compared to other businesses within Kentucky. Furthermore, he pointed out inconsistencies in how these taxes were applied to different entities, which further underscored his belief in their unconstitutionality. This unjust treatment, according to him, could potentially discourage or hinder interstate commerce activities by creating an unfair playing field for certain types of businesses.