Law, generally signifies one who has the charge of the person, education, and property of children, or of any one labouring under some incapacity for managing his own affairs. A father is by nature the guardian of his children. On his death the office is devolved on those who may have been appointed by him, or if they decline to accept, the law appoints the nearest relatives on the father's side. The Roman law, in the event of no appointment by the father, generally committed the guardianship of both the minor and his estate to him who, by the death of the minor, would succeed to his inheritance; presuming that he would take the best care of the estate who had the nearest prospect of succeeding to it. But both the law of England and Scotland commit only the care of the estate to the heir-apparent; and, wisely considering that he may not be sufficiently careful of a life standing in the way of his own succession, intrust the custody of the pupil to the mother if alive, or, if dead, to the nearest relatives on the mother's side. Guardians may also be appointed by a stranger for the management of an estate left to the minor by such stranger, or by a judge before whom a suit may depend, in which a father may have an interest adverse to his child; and in all cases where, from any cause, a person cannot manage his own affairs, and his relatives are unwilling or disqualified to act for him, the law, in one form or another, provides a manager or guardian. In these last cases, security, and a strict account of his intromissions, are exacted from the guardian. The guardianship of a father over his minor daughter is at an end when she marries a person who has attained majority—the husband being the guardian of his wife.

Both in England and in Scotland, as by the Roman law, guardians are appointed for the protection of the persons and estates of idiots and lunatics. Guardians for children are distinguished as tutors and curators. The former act altogether in the place of the pupil, who is held incapable of giving consent; and the latter act along with the minor (that is a person past puberty, but still under majority), who is not held incapable, though immature. The powers of both of these guardians resemble those of a parent; and may be comprehended in the word administration, or management. They can neither sell their ward's estate, nor alter its succession.

In Scotland, the court, on evidence that a person of full age is of a weak and facile disposition and wasteful habits, will appoint, and such a person may even by his own voluntary act appoint, a guardian, called an interdictor, without whose consent (the public being previously warned in a prescribed form) he can do nothing towards the alienation of his heritable estate. This sort of guardianship can only be removed by the court on evidence, either that it was originally unnecessary, or that the party has become provident of his own affairs; or, when constituted voluntarily, by the consent or death of the interdictor.