Parker Doctrine refers to the principle laid down by the Supreme Court in Parker v. Brown, 317 U.S. 341 (U.S. 1943), that states are immune from federal antitrust law for their actions as sovereigns. In Parker, a raisin distributor, Porter Brown, challenged a 1940 California regulation that raised prices and restricted the supply of California raisins. The Court found that the Sherman Act contained neither a hint nor a suggestion of any intention "to restrain state action or official action directed by a state." The Sherman Act's antitrust laws did not apply to state actions, and thus California's regulation of the raisin industry was immune from federal antitrust scrutiny. However if private individuals made the same act, such actions would be in violation of the law. The Court also determined that the Act did not offend the Commerce Clause, since it was in conformity with the policies of Congress, and did not directly conflict with federal law.
Parker Doctrine is also known as State-Action Doctrine.