In the Duke Power Co. et al. v. Greenwood County et al., 1937, the Supreme Court of the United States ruled in favor of Duke Power Company and against Greenwood County, South Carolina regarding a dispute over power production rights on Lake Keowee. The case arose when Greenwood County sought to construct its own hydroelectric plant on Lake Keowee, which was already being utilized by Duke Power for electricity generation under a license from Federal Power Commission (FPC). The county argued that it had inherent right as a municipality to use water resources within its boundaries without federal interference or regulation. However, the Supreme Court held that even though municipalities have certain privileges under state law, they are still subject to federal laws and regulations concerning navigable waters and their usage for power production purposes. Therefore, any entity wishing to utilize such resources must comply with relevant federal statutes including obtaining necessary permits or licenses from FPC regardless of their status as private companies or public bodies like counties or cities.

In the dissenting opinion for Duke Power Co. et al. v. Greenwood County et al., Justice Black argued that the majority's decision to allow a state-created power company to compete with private companies was unconstitutional and went against previous court decisions which had established limits on states' ability to engage in business activities. He contended that this ruling would open up opportunities for states to create monopolies, thereby undermining free competition and violating citizens' right to earn a living through their own businesses. Furthermore, he expressed concern about potential abuses of power by these state-run entities due to lack of accountability and oversight mechanisms typically present in privately run businesses.