The U.S. Supreme Court case Greyhound Corp. et al. v. Mt. Hood Stages, Inc., DBA Pacific Trailways in 1977 revolved around the issue of antitrust laws and their application to interstate bus companies such as Greyhound Corporation and Mount Hood Stages (doing business as Pacific Trailways). The court had to decide whether the Interstate Commerce Commission (ICC) was correct in granting immunity from antitrust laws for certain agreements between these companies under Section 5(11) of the Interstate Commerce Act, which allows for approval of mergers or acquisitions that are "in the public interest". The Supreme Court held that ICC's grant of immunity did not violate any statutory requirements nor did it exceed its authority under Section 5(11). It further ruled that an agreement approved by ICC is immune from antitrust action unless there is a showing that ICC exceeded its jurisdiction when approving said agreement.

In the dissenting opinion for Greyhound Corp. et al. v. Mt. Hood Stages, Inc., DBA Pacific Trailways, Justice Rehnquist disagreed with the majority's interpretation of Section 5(2)(b) of the Interstate Commerce Act and its application to this case involving bus companies' acquisition agreements. He argued that Congress intended for a more comprehensive review by the Commission before approving any transaction under Section 5(2)(b). The majority's decision allowed an agreement between two carriers without considering whether it would diminish competition or harm public interest - factors he believed were critical in such cases according to legislative intent behind this provision of law. Furthermore, he criticized their reliance on precedent from railroad cases which had different regulatory contexts and should not be applied uniformly to all transportation industries.