The Holt et al. v. Alleghany Corp et al., 1965 case revolved around the issue of whether a merger between two railroad companies, namely the Chesapeake and Ohio Railway Company (C&O) and the New York Central Railroad Company (NYC), was subject to approval by the Interstate Commerce Commission (ICC). The Supreme Court held that since C&O had acquired control over NYC through its purchase of shares in Alleghany Corporation, which owned most of NYC's stock, it constituted a "control" transaction under Section 5(2) of the Interstate Commerce Act. Therefore, ICC approval was required before such a merger could take place. This decision underscored that indirect acquisitions or changes in control involving rail carriers were also within ICC’s jurisdiction.

In the dissenting opinion for Holt et al. v. Alleghany Corp. et al., Justice Harlan disagreed with the majority's interpretation of Section 5(b) of the Interstate Commerce Act, arguing that it was not intended to cover transactions like those in question in this case - a merger between two holding companies neither of which directly engaged in transportation activities regulated by the Act. He argued that such an expansive reading would result in unnecessary federal regulation and could potentially stifle business innovation and growth due to excessive oversight from regulatory bodies such as ICC (Interstate Commerce Commission). Furthermore, he expressed concern over potential jurisdictional conflicts between different regulatory agencies if non-transportation related mergers were subjected to ICC approval under Section 5(b). Lastly, he criticized the majority’s reliance on legislative history rather than clear statutory language or precedent cases when interpreting Section 5(b), stating that it led them to an incorrect conclusion about its scope.