The Parker immunity doctrine is an exemption from liability for engaging in antitrust violations. It applies to the state when it exercises legislative authority in creating a regulation with anticompetitive effects, and to private actors when they act at the direction of the state after it has done so. The doctrine is named for the Supreme Court of the United States case in which it was initially developed, Parker v. Brown. The rationale behind Parker immunity is that Congress, in enacting the Sherman Act, evidenced no intent to restrain state behavior.