In the 1936 case of DuPont et al. v. United States, the Supreme Court ruled that E.I du Pont de Nemours & Company and its associated companies were in violation of antitrust laws due to their control over a significant portion of the U.S gunpowder market. The court found that DuPont had used various methods, including exclusive contracts and price manipulation, to maintain an unlawful monopoly on military and commercial explosives manufacturing and sales. This decision was based on Section 2 of the Sherman Act which prohibits monopolization or attempts at monopolizing any part of trade or commerce among states or with foreign nations. As a result, DuPont was ordered by the court to divest some assets related to these operations in order to reduce its market dominance.

In the dissenting opinion for DuPont et al. v. United States, it was argued that the majority's decision to uphold a lower court ruling against E.I du Pont de Nemours & Company and its co-defendants violated principles of fair competition and free enterprise. The dissenting justices contended that the defendants were not guilty of conspiracy to monopolize or restrain trade in violation of Sherman Antitrust Act as they had merely engaged in normal business practices such as purchasing stock in rival companies and entering into non-compete agreements with other firms. They further asserted that these actions did not constitute an unreasonable restraint on commerce but rather promoted efficiency and economic growth by allowing businesses to collaborate, innovate, and compete effectively in a rapidly evolving market environment.