The United States Congress, pursuant to 15 U.S.C. §15(c), known as the Parens Patriae Act, has given to state attorney generals the right to bring claims on behalf of their states’ citizens, under 15 U.S.C. Sections 1-7, i.e., the Sherman Act and the merger provisions of the Clayton Act. This is the reason some cases cannot easily be settled without the consent of the states attorneys general participating in the case.
The best-known example of this type of suit was the Microsoft antitrust case where the states were participants in parens patriae. In the context of currently relatively lax Federal government enforcement of U.S. antitrust law, this provision is of increasing importance. The origin of the term was a legal rule that allowed courts (as an organ of the state) to make decisions on behalf of those who were incompetent or unable to make the decisions on their own behalf, e.g., minors and the mentally ill. The words in parens patriæ mean literally “as the father of his country” and signified that the state was regarded as the ultimate guardian of all its citizens and could act as a parent or guardian for one, where no one else was willing or able to serve in that capacity.