In the case of Hoover et al. v. Ronwin et al., 1983, the United States Supreme Court ruled that a state bar examination, administered by a committee of the state supreme court, was not considered "action under color of state law" and therefore did not fall within federal jurisdiction as per Section 1 of Sherman Act (an antitrust law). The plaintiff in this case was Gary Ronwin who failed to pass Arizona's bar exam and sued on grounds that it violated his rights because it limited competition among lawyers. However, Justice Thurgood Marshall wrote for the majority opinion stating that since there is no commercial aspect involved in administering a bar exam or setting its passing score - these actions are part of states' sovereign power to regulate professions like practicing law - they cannot be subjected to federal antitrust laws.

In the dissenting opinion for Hoover et al. v. Ronwin et al., Justice Blackmun argued that the Arizona Supreme Court's decision to delegate its bar admission authority to a committee should not grant immunity from federal antitrust laws. He contended that this delegation did not transform private conduct into state action, and thus, it was inappropriate to extend Parker immunity in this case. The justice also expressed concern about the majority’s broad interpretation of "state action," fearing it could potentially shield other private entities from federal regulation simply because they were executing some delegated state power. Furthermore, he disagreed with the majority's view on competitive restraint as an inherent aspect of a licensing system; instead, he believed such restraints must be actively supervised by states if they are to enjoy exemption from antitrust scrutiny.