In the case of New England Power Co. v. New Hampshire et al., 1981, the U.S Supreme Court ruled that a state cannot prevent an electric utility company from selling its excess power to out-of-state customers at higher rates than it charges in-state customers if approved by Federal Energy Regulatory Commission (FERC). The court held that such restrictions violated the Commerce Clause of the Constitution which prohibits states from interfering with interstate commerce. In this case, New England Power Company wanted to sell surplus energy generated in New Hampshire to other states where they could get better prices but was barred by a law enacted by the State of New Hampshire. The Supreme Court's decision affirmed that only FERC has jurisdiction over wholesale electricity sales and not individual states.

In the dissenting opinion for New England Power Co. v. New Hampshire et al., Justice Harry Blackmun argued that the majority's decision was an overreach of federal authority and a disregard for state sovereignty. He contended that the Federal Power Act did not preempt states from regulating wholesale electricity sales, as long as they were not discriminatory or in conflict with federal regulations. According to him, New Hampshire's law requiring utilities to sell excess power back to their customers at retail rates was neither discriminatory nor conflicting with any specific provision of federal law or regulation by FERC (Federal Energy Regulatory Commission). Therefore, he believed it should have been upheld rather than struck down on preemption grounds. Furthermore, he expressed concern about potential negative impacts on energy conservation efforts resulting from this ruling.