par·ens pat·ri·ae /'par-ənz-'pa-trē-ˌē, -'pā-, -trē-ˌī; 'pär-ens-'pä-trē-ˌī/ n [Latin, parent of the country]: the state in its capacity as the legal guardian of persons not sui juris and without natural guardians, as the heir to persons without natural heirs, and as the protector of all citizens unable to protect themselves
because the State is supposed to proceed in respect of the child as parens patriae and not as adversary — Kent v. United States, 383 U.S. 541 (1966)
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.