The United States Supreme Court case, UNITED STATES v. EL PASO NATURAL GAS CO. et al., 1963, revolved around the acquisition of Pacific Northwest Pipeline Corporation by El Paso Natural Gas Company and whether it violated Section 7 of the Clayton Act which prohibits mergers that may reduce competition or create a monopoly. The government argued that El Paso's purchase would eliminate potential competition between the two companies in California's natural gas market. The court ruled in favor of the government stating that even though Pacific was not currently competing with El Paso, they were capable of doing so and thus their merger could potentially lessen future competition. Therefore, this acquisition did violate antitrust laws as per Section 7 of the Clayton Act.

In the dissenting opinion for the United States v. El Paso Natural Gas Co. et al., it was argued that the majority's decision to order divestiture as a remedy for an antitrust violation was too severe and unnecessary in this case. The dissenting justices believed that there were other, less drastic remedies available that could have effectively restored competition without causing undue harm to El Paso Natural Gas Company or its shareholders. They also disagreed with the majority's interpretation of Section 7 of the Clayton Act, arguing that it should not be applied so broadly as to prohibit all mergers and acquisitions between competitors unless they can prove their actions would not lessen competition in any way whatsoever. This overly strict interpretation, they contended, went beyond what Congress intended when it enacted Section 7 and could potentially stifle legitimate business growth and innovation.