In the case of Buck et al. v. Gallagher, State Treasurer, et al., in 1938, the Supreme Court examined whether a Minnesota law that taxed telephone companies based on their gross earnings was constitutional. The appellants were two out-of-state telephone companies who argued that this tax violated both the Due Process Clause and Commerce Clause of the U.S Constitution because it included interstate business revenue within its calculation for taxation purposes. However, the court upheld Minnesota's right to impose such taxes on these corporations operating within its borders as long as they are fairly apportioned and do not discriminate against interstate commerce or cause multiple states to tax more than 100% of a company’s income from an activity connected with several jurisdictions (i.e., no double taxation). In conclusion, while acknowledging that some portion of these taxes may have been derived from interstate operations which could be constitutionally immune from state taxation under certain circumstances, there was insufficient evidence presented by appellants to demonstrate any unconstitutional burden imposed upon them due to this particular method used by Minnesota for taxing businesses.

In the dissenting opinion for Buck et al. v. Gallagher, State Treasurer, et al., Justice McReynolds disagreed with the majority's decision to uphold a Minnesota law that required insurance companies operating in multiple states to invest assets equal to their policy reserves within each state they operated in. He argued that this law violated the Commerce Clause of the U.S Constitution by placing an undue burden on interstate commerce and discriminating against out-of-state businesses. Furthermore, he contended that it was not within a state's power to regulate how an insurance company manages its funds outside of ensuring solvency and protecting policyholders' interests; anything beyond this would be overreach into areas reserved for federal regulation or private business decisions.