Throughout the history of Roman law a child under the age of puberty needed a guardian and so also at the time of the XII Tables (and for long afterwards) did a woman of any age who was sui iuris. In these cases the guardian was called tutor. Beyond incapacity due to youth or sex Roman law also recognised two other cases, that of the lunatic (furiosus) and the spendthrift (prodigus), but in these cases the guardian was called by a different name –curator–. It must however be understood that there is never any question of guardianship of either sort except where the person concerned is sui iuris; a person who is in potestate, in manu or in mancipio can have no guardian, because the chief function (and in later law the only function) of the guardian is to administer the property of the incapable person, and a person alieni iuris can have no property to be administered.
At the time of the XII Tables the rules for the appointment of tutores were simple in the extreme. A man might in his will appoint a tutor for any person in his manus or potestas who would become sui iuris at his death. Failing a tutor appointed by will, the tutela went, in the case of free-born persons, to the nearest male agnate (i.e. to the person most closely related, relationship being reckoned through males exclusively), or nearest agnates jointly, if there were several related in the same degree; failing agnates it went to the gentiles. In the case of freed persons (who could have no agnates) the tutela went to the patron (i.e. the person who had manumitted them) or his children. This was not definitely laid down by the XII Tables, but was inferred from the rule that the patron or his children were to take the succession to freed persons if they died intestate.