Parens patriae is Latin for "parent of the nation" (lit., "parent of the fatherland"). In law, it refers to the public policy power of the state to intervene against an abusive or negligent parent, legal guardian or informal caretaker, and to act as the parent of any child or individual who is in need of protection. For example, some children, incapacitated individuals, and disabled individuals lack parents who are able and willing to render adequate care, thus requiring state intervention.
In U.S. litigation, parens patriae can be invoked by the state to create its standing to sue; the state declares itself to be suing on behalf of its people. For example, the Hart-Scott-Rodino Antitrust Improvement Act of 1976 (15 USC 15c), through Section 4C of the Clayton Act, permits state attorneys general to bring parens patriae suits on behalf of those injured by violations of the Sherman Antitrust Act.
Parens patriae relates to a notion initially invoked by the King's Bench in the sixteenth century in cases of non compos mentis adults. The notion dates from at least 1608, as recorded in Coke's Report of Calvin's Case, wherein it is said "that moral law, honora patrem...doubtless doth extend to him that is pater patriæ."
The parens patriae doctrine was gradually applied to children throughout the seventeenth and eighteenth centuries, and has since evolved from one granting absolute rights to the sovereign to one more associated with rights and obligations of the state and courts towards children and incapacitated adults.
In most jurisdictions, this appears in the principle that makes the protection of the best interests of any child the first and single most important concern of the courts. For example, in any proceedings affecting the validity of a marriage, the children will not be parties in their own right, nor will they be parties to any agreement that the spouses may make. In these proceedings, the courts will often be invited to accept and enforce any agreement between a husband and wife regarding parental responsibility for their children. This will usually be done so long as the agreement is seen to be in the best interests and welfare of the children. Courts are not obliged to invoke the parens patriae doctrine in cases involving children and not all courts, particularly newer courts such as the Australian Family Court (est 1975), have specific parens patriae jurisdiction.