The National Society of Professional Engineers v. United States case in 1977 revolved around the issue of whether a professional society's canon, which prohibited competitive bidding for engineering services, violated antitrust laws. The National Society of Professional Engineers argued that their ethical code was necessary to ensure high-quality service and prevent price competition from compromising safety standards. However, the Supreme Court ruled against them unanimously (9-0), stating that any agreement restraining trade or commerce is illegal under Section 1 of the Sherman Act unless it can be justified as reasonable. The court held that public safety concerns could not justify an absolute ban on competitive bidding because these issues should be addressed through legislation rather than private market manipulation by a group with self-interests at stake.

In the dissenting opinion for the case of National Society of Professional Engineers v. United States, Justice Rehnquist argued that the majority's decision to apply antitrust laws to a professional organization was misguided. He contended that such organizations are fundamentally different from commercial enterprises and should not be subject to the same regulations. In his view, applying these rules could potentially harm public safety by forcing engineers to compete on price rather than quality or competence. Furthermore, he criticized the majority for failing to consider whether Congress intended for antitrust laws to apply in this context when they were originally enacted.