parens patriae

Definition from Nolo’s Plain-English Law Dictionary

(par-ens pa-tree-ee) Latin for "parent of his or her country." The power of the state to act as guardian for those who are unable to care for themselves, such as children or disabled individuals. For example, under this doctrine a judge may change custody, child support, or other rulings affecting a child's well-being, regardless of what the parents may have agreed to.

Definition provided by Nolo’s Plain-English Law Dictionary.