In the case of United States v. National City Lines, Inc., et al., 1948, the U.S. Supreme Court addressed allegations that several major corporations had conspired to monopolize sales of buses and supplies to local transit companies throughout various cities in America. The defendants included General Motors Corporation, Standard Oil Company of California (now Chevron), Firestone Tire & Rubber Company among others who were accused under sections 1 and 2 of the Sherman Act for acquiring control over a number of transportation systems, essentially replacing electric streetcars with petroleum-powered buses across twenty-five states. This conspiracy was known as "the Great American Streetcar Scandal". The court found these corporations guilty on one count out of two - conspiring to monopolize interstate commerce among themselves but not guilty on charges related directly towards public transportation due to lack evidence proving intent or successful monopoly within city transport services.

The dissenting opinion in the United States v. National City Lines, Inc., et al., case argued that the majority's interpretation of Section 3 of the Clayton Act was too broad and could potentially criminalize normal business activities. The dissenters believed that a more narrow reading of this section should have been applied, one which would only prohibit actions specifically intended to create or maintain a monopoly. They also disagreed with the majority's conclusion that there was sufficient evidence to prove an intent to monopolize on part of defendants. Furthermore, they criticized how lower courts handled certain evidentiary matters during trial proceedings and expressed concerns about potential violations of due process rights for defendants.