In the case of Mountain States Power Co. v. Public Service Commission of Montana, 1936, the Supreme Court ruled on a dispute between a power company and state regulatory commission over rates for electricity services. The Mountain States Power Company challenged an order by the Public Service Commission of Montana that reduced its rates, arguing it was confiscatory and violated their constitutional rights under the Fourteenth Amendment's due process clause. However, after reviewing evidence presented about operating costs and potential revenues at these lower rates, as well as considering other factors such as depreciation and taxes, the court found no basis to overturn this decision by state regulators. Therefore, they upheld that states have broad powers to regulate public utilities within their jurisdiction including setting reasonable rate structures in line with providing adequate service while ensuring fair returns for utility providers.

The dissenting opinion in the Mountain States Power Co. v. Public Service Commission of Montana case argued that the majority's decision to strike down a state law regulating utility rates was an overreach of judicial power and violated principles of federalism. The dissenters believed that states should have broad authority to regulate businesses within their borders, including setting fair and reasonable rates for public utilities like electricity. They contended that it is not the role of courts to second-guess these policy decisions unless they are clearly unreasonable or discriminatory, which they did not believe was true in this case. Furthermore, they expressed concern about the potential implications of this ruling on other state regulatory efforts and warned against undermining states' ability to protect consumers from unfair business practices.