A more thorough explanation:

The state-action doctrine is a principle in antitrust law that states that the antitrust laws do not prohibit a state's anticompetitive acts or official acts directed by a state. This means that if a state engages in actions that would otherwise be considered anticompetitive, they are exempt from antitrust laws.

For example, in the case of Parker v. Brown, the Supreme Court ruled that California's Agricultural Prorate Act, which allowed the state to regulate the sale of raisins, was exempt from antitrust laws because it was a state action. Similarly, if a state creates a licensing board that regulates a particular industry, the board's actions may be exempt from antitrust laws.

The Midcal test is a doctrine in antitrust law that determines whether the anticompetitive acts of a private party are considered state acts and therefore protected from liability under antitrust laws. To be considered a state act, the conduct must be within a clearly articulated and affirmatively expressed policy of the state and actively supervised by the state.

For example, in the case of California Retail Liquor Dealers Ass'n v. Midcal Aluminum, Inc., the Supreme Court ruled that California's Alcoholic Beverage Control Act, which allowed the state to regulate the sale of alcoholic beverages, was a clearly articulated and affirmatively expressed policy of the state. The Court also found that the state actively supervised the conduct of the private parties involved in the regulation of the sale of alcoholic beverages, which meant that their actions were exempt from antitrust laws.