In the case of Federal Trade Commission v. Dean Foods Co., the Supreme Court ruled in favor of the FTC, granting it authority to seek preliminary injunctions against corporate mergers that could potentially violate antitrust laws. The FTC had sought to prevent a merger between Dean Foods and Bowman Dairy Company, arguing that it would significantly reduce competition in the dairy industry within certain markets. However, lower courts initially denied this request on grounds that Section 13(b) of the Federal Trade Commission Act did not explicitly grant such power to FTC. Upon appeal by FTC, though, SCOTUS reversed these decisions stating that while explicit statutory authority was absent for seeking injunctive relief under section 13(b), there existed an inherent equity jurisdiction conferred upon all federal courts which allowed them to issue injunctions under appropriate circumstances even if no specific statute authorized such action.

The dissenting opinion in the Federal Trade Commission v. Dean Foods Co. case argued that the majority's decision to grant preliminary injunctions was a significant departure from established legal principles and could potentially undermine the authority of administrative agencies like FTC. The dissenters believed that such an action should only be taken when there is clear evidence of irreparable harm, which they did not believe existed in this case. They also expressed concern about judicial overreach, arguing that courts should refrain from intervening in ongoing administrative proceedings unless absolutely necessary for justice. Furthermore, they warned against setting a precedent where federal courts can interfere with pending agency actions based on speculative future harms or potential violations.