Black's Law Dictionary, Sixth Edition, p. 1114

Parens patriae.  "Parens patriae," literally "parent of the country," refers traditionally to role of state as sovereign and guardian of persons under legal disability, such as juveniles or the insane, State of W.Va. v. Chas. Pfizer & Co., C.A.N.Y., 440 F.2d 1079, 1089, and in child custody determinations, when acting on behalf of the state to protect the interests of the child.  It is the principle that the state must care for those who cannot take care of themselves, such as minors who lack proper care and custody from their parents.  It is a concept of standing utilized to protect those quasi-sovereign interests such as health, comfort and welfare of the people, interstate water rights, general economy of the state, etc.  Gibbs v. Titelman, D.C.Pa., 369 F.Supp. 38, 54.

[Black's Law Dictionary, Sixth Edition, p. 1114]