In the Duke Power Co. v. Greenwood County case of 1936, the U.S Supreme Court ruled in favor of Duke Power Company, asserting that Greenwood County was not exempt from paying for electricity used at a county-owned and operated cotton mill under South Carolina law. The court held that while counties were generally immune from lawsuits, this immunity did not extend to commercial activities such as running a cotton mill. Therefore, Greenwood County's operation of a cotton mill constituted proprietary rather than governmental functions and thus could be sued by private entities like Duke Power Company for unpaid services rendered.

The dissenting opinion in the Duke Power Co. et al. v. Greenwood County et al., case argued that the Federal Power Act did not grant the Federal Power Commission (FPC) jurisdiction over all hydroelectric power projects, but only those located on navigable waters or federal lands, and those which utilize surplus water from a government dam. The dissent contended that since none of these conditions applied to Greenwood County's proposed project, it should be outside FPC’s purview. They also pointed out inconsistencies in how majority interpreted certain sections of the act and believed this interpretation could lead to an unwarranted expansion of federal control over local utilities.