In the case of Civil Aeronautics Board et al. v. American Air Transport, Inc. et al., 1952, the Supreme Court dealt with issues related to air transport regulation and competition law in aviation industry. The dispute arose when American Air Transport (AAT) filed a complaint against four major airlines alleging that they had conspired to monopolize air traffic by controlling key routes and engaging in predatory pricing practices which violated antitrust laws. The Civil Aeronautics Board (CAB), however, dismissed this complaint on grounds that it lacked jurisdiction over such matters as these were within purview of federal courts under Sherman Act. The Supreme Court upheld CAB's decision stating that while CAB did not have authority to enforce antitrust laws directly, it was empowered by Federal Aviation Act to regulate airline fares and prevent unfair competitive practices including those amounting to monopoly or restraint of trade indirectly through its rate-making powers and certification process for new carriers/routes etc., thus providing an administrative remedy for such complaints before resorting to judicial action under Sherman Act.

The dissenting opinion in the case of Civil Aeronautics Board et al. v. American Air Transport, Inc. et al., argued that the majority's decision was a misinterpretation of the Federal Aviation Act and an overreach by regulatory authorities. The dissenters believed that Congress did not intend for airlines to be regulated so heavily as to prevent them from making independent business decisions about their routes and services offered, which they saw as essential aspects of competition within a free market system. They also expressed concerns about due process rights being violated because airlines were not given adequate opportunity to challenge or appeal regulatory decisions before they were enforced by government agencies like the Civil Aeronautics Board (CAB). Furthermore, they disagreed with how CAB defined "public convenience" when deciding whether or not to approve new airline routes; arguing it should consider more than just current demand but also potential future growth opportunities for both individual companies and industry overall.