Minor minorem custodire non debet
Minor minorem custodire non debet, alios enim praesumitur male regere qui seipsum regere nuscit. A minor ought not to be guardian of a minor, for he is unfit to govern others who does not know how to govern himself. Co. Litt. 88.
A Law Dictionary, Adapted to the Constitution and Laws of the United States. By John Bouvier. Published 1856.