In the 1904 Supreme Court case American Express Company v. Iowa, the court ruled in favor of American Express Company (AmEx). The state of Iowa had imposed a tax on AmEx for conducting business within its borders without having an office or property there. The company argued that this was unconstitutional as it violated their rights under the Fourteenth Amendment's Due Process Clause and Commerce Clause. The Supreme Court agreed with AmEx, stating that while states have power to regulate commerce within their boundaries, they cannot impose taxes on interstate commerce activities such as those conducted by express companies like AmEx. This decision reinforced the principle that states cannot interfere with interstate commerce through taxation.

In the dissenting opinion for the case American Express Company v. Iowa, it was argued that the majority's decision to exempt express companies from taxation in states where they do not have a physical presence is fundamentally flawed. The dissenting justices contended that this interpretation of interstate commerce disregards state sovereignty and undermines their ability to levy taxes on businesses operating within their borders, regardless of whether these businesses maintain offices or other facilities there. They further asserted that such an exemption could lead to unequal treatment among different types of corporations and potentially encourage tax evasion by encouraging companies to operate without establishing a physical presence in certain states. This view holds that all corporations should be subject to taxation under equal terms as long as they are conducting business within a state's jurisdiction.