The United States v. Socony-Vacuum Oil Co., Inc. et al., 1939, was a landmark case that affirmed the government's authority to regulate price-fixing activities under the Sherman Antitrust Act of 1890. The defendants, major oil companies including Standard Oil and Socony-Vacuum, were accused of conspiring to raise gasoline prices by purchasing excess supplies in order to limit market availability and manipulate pricing - an act known as "hot oil" transactions. They argued that their actions did not directly set prices but merely stabilized them in a volatile market situation during the Great Depression era. However, the Supreme Court ruled unanimously against this argument stating any form of price manipulation or control is illegal per se under antitrust laws regardless of its impact on competition or justifications provided for economic stability purposes.

In the dissenting opinion for United States v. Socony-Vacuum Oil Co., Inc., Justice McReynolds argued that the majority's decision was based on a misunderstanding of economic principles and an overreach of judicial power. He contended that price-fixing, in this case, did not necessarily equate to market manipulation or monopolistic practices as it could also be seen as a legitimate business strategy aimed at stabilizing volatile markets during challenging times such as the Great Depression when this case occurred. Furthermore, he criticized the majority's reliance on public policy considerations rather than strict legal analysis in reaching their conclusion. According to him, it is Congress' role to legislate against perceived social ills like price fixing if they deem necessary; courts should only interpret existing laws and not create new ones through their rulings.