The law, however, is not completely satisfied by the observance of the rules hereinbefore explained. A testator who has a son in his power must take care either to institute him heir, or to specially disinherit him, for passing him over in silence avoids the will; and this rule is so strict, that even if the son die in the lifetime of the father no heir can take under the will, because of its original nullity. As regards daughters and other descendants of either sex by the male line, the ancients did not observe this rule in all its strictness; for if these persons were neither instituted nor disinherited, the will was not avoided, but they were entitled to come in with the instituted heirs, and to take a certain portion of the inheritance. And these persons the ascendant was not obliged to specially disinherit; he could disinherit them collectively by a general clause.

1 Special disinherison may be expressed in these terms—'Be Titius my son disinherited,' or in these, 'Be my son disinherited,' without inserting the name, supposing there is no other son. Children born after the making of the will must also be either instituted heirs or disinherited, and in this respect are similarly privileged, that if a son or any other family heir, male or female, born after the making of the will, be passed over in silence, the will, though originally valid, is invalidated by the subsequent birth of the child, and so becomes completely void. Consequently, if the woman from whom a child was expected to have an abortive delivery, there is nothing to prevent the instituted heirs from taking the inheritance. It was immaterial whether the female family heirs born after the making of the will were disinherited specially or by a general clause, but if the latter mode be adopted, some legacy must be left them in order that they may not seem to have been passed over merely through inadvertence: but male family heirs born after the making of the will, sons and other lineal descendants, are held not to be properly disinherited unless they are disinherited specially, thus: 'Be any son that shall be born to me disinherited.'

2 With children born after the making of the will are classed children who succeed to the place of a family heir, and who thus, by an event analogous to subsequent birth, become family heirs to an ancestor. For instance, if a testator have a son, and by him a grandson or granddaughter in his power, the son alone, being nearer in degree, has the right of a family heir, although the grandchildren are in the testator's power equally with him. But if the son die in the testator's lifetime, or is in some other way released from his power, the grandson and granddaughter succeed to his place, and thus, by a kind of subsequent birth, acquire the rights of family heirs. To prevent this subsequent avoidance of one's will, grandchildren by a son must be either instituted heirs or disinherited, exactly as, to secure the original validity of a testament, a son must be either instituted or specially disinherited; for if the son die in the testator's lifetime, the grandson and granddaughter take his place, and avoid the will just as if they were children born after its execution. And this disinherison was first allowed by the lex Iunia Vallaea, which explains the form which is to be used, and which resembles that employed in disinheriting family heirs born after the making of a will.

3 It is not necessary, by the civil law, to either institute or disinherit emancipated children, because they are not family heirs. But the praetor requires all, females as well as males, unless instituted, to be disinherited, males specially, females collectively; and if they are neither appointed heirs nor disinherited as described, the praetor promises them possession of goods against the will.

4 Adopted children, so long as they are in the power of their adoptive father, are in precisely the same legal position as children born in lawful wedlock; consequently they must be either instituted or disinherited according to the rules stated for the disinherison of natural children. When, however, they have been emancipated by their adoptive father, they are no longer regarded as his children either by the civil law or by the praetor's edict. Conversely, in relation to their natural father, so long as they remain in the adoptive family they are strangers, so that he need neither institute nor disinherit them: but when emancipated by their adoptive father, they have the same rights in the succession to their natural father as they would have had if it had been he by whom they were emancipated. Such was the law introduced by our predecessors.

5 Deeming, however, that between the sexes, to each of which nature assigns an equal share in perpetuating the race of man, there is in this matter no real ground of distinction, and marking that, by the ancient statute of the Twelve Tables, all were called equally to the succession on the death of their ancestor intestate (which precedent the praetors also seem to have subsequently followed), we have by our constitution introduced a simple system of the same kind, applying uniformly to sons, daughters, and other descendants by the male line, whether born before or after the making of the will. This requires that all children, whether family heirs or emancipated, shall be specially disinherited, and declares that their pretermission shall have the effect of avoiding the will of their parent, and depriving the instituted heirs of the inheritance, no less than the pretermission of children who are family heirs or who have been emancipated, whether already born, or born after, though conceived before the making of the will. In respect of adoptive children we have introduced a distinction, which is explained in our constitution on adoptions.

6 If a soldier engaged on actual service makes a testament without specially disinheriting his children, whether born before or after the making of the will, but simply passing over them in silence, though he knows that he has children, it is provided by imperial constitutions that his silent pretermission of them shall be equivalent to special disinherison.

7 A mother or maternal grandfather is not bound to institute her or his children or grandchildren; they may simply omit them, for silence on the part of a mother, or of a maternal grandfather or other ascendant, has the same effect as actual disinherison by a father. For neither by the civil law, nor by that part of the praetor's edict in which he promises children who are passed over possession of goods against the will, is a mother obliged to disinherit her son or daughter if she does not institute them heirs, or a maternal grandfather to be equally precise with reference to grandchildren by a daughter: though such children and grandchildren, if omitted, have another remedy, which will shortly be explained.