In the 1966 case of Cascade Natural Gas Corp. v. El Paso Natural Gas Co., the U.S Supreme Court ruled in favor of Cascade, finding that El Paso had violated antitrust laws by acquiring Pacific Northwest Pipeline Corporation and subsequently eliminating it as a competitor in the natural gas market. The court found that this acquisition was an attempt to monopolize interstate commerce, which is prohibited under Section 2 of the Sherman Act. As a result, El Paso was ordered to divest itself from Pacific Northwest Pipeline Corporation and any other companies it had acquired during its attempted monopoly.

The dissenting opinion in the case of CASCADE NATURAL GAS CORP. v. EL PASO NATURAL GAS CO., et al., argued that the majority's decision to order divestiture was too extreme and unnecessary given the circumstances of the case. The dissenters believed that there were other, less drastic remedies available to address any antitrust concerns raised by El Paso Natural Gas Co.'s acquisition of Pacific Northwest Pipeline Corp. They also expressed concern about potential negative impacts on innocent third parties who had invested in or done business with these companies based on their existing structure and operations at the time of purchase. Furthermore, they questioned whether it was appropriate for a court to intervene so directly in market dynamics without clear evidence demonstrating harm from reduced competition or monopolistic practices.