The United States Supreme Court case, UNITED SHOE MACHINERY CORPORATION et al. v. UNITED STATES, 1921 revolved around antitrust laws and monopolistic practices in the shoe machinery industry. The United Shoe Machinery Corporation was accused by the U.S government of violating the Sherman Antitrust Act through its leasing system that required lessees to use its machines exclusively for all their requirements, thus creating a monopoly and stifling competition. The corporation defended itself arguing that it did not sell but only leased out its machines which should exempt them from such accusations as per existing interpretations of law at that time. However, after careful consideration of arguments presented by both sides, the court ruled against United Shoe Machinery Corporation stating that regardless of whether they sold or leased their products; if their actions resulted in restraint of trade and creation of monopoly then they were indeed guilty under antitrust laws.

In the dissenting opinion for UNITED SHOE MACHINERY CORPORATION et al. v. UNITED STATES, Justice McReynolds disagreed with the majority's view that United Shoe Machinery Corporation had violated antitrust laws by leasing rather than selling its machinery and tying leases to use of its supplies. He argued that these practices were not inherently illegal and should only be considered so if they unreasonably restrained trade or monopolized a part of it. He believed there was insufficient evidence to prove such an effect in this case, as competitors still existed in the market despite United's dominant position. Furthermore, he pointed out that customers willingly entered into lease agreements because they found them beneficial due to lower upfront costs compared to purchasing machines outright and receiving regular maintenance services from United Shoe Machinery Corporation.