Constantinus, a. d. 355, restored the ancient law and prohibited marriage with a brother’s daughter as incestuous, Cod. Theod. 3, 12, 1.
Affinity (affinitas) is the relationship of a person to the kin (cognates) of a spouse. The husband is allied to the kin of the wife, the wife to the kin of the husband; but there is no alliance between the kin of the husband and the kin of the wife. The following are some of the names given to these relationships. In the ascending line the father and mother of the wife or husband are socer and socrus (father-in-law, mother-in-law), and in relation to them the husband of the daughter and wife of the son are gener and nurus (son-in-law, daughter-in-law). In the descending line the children of the spouse are privignus and privigna (step-son, step-daughter), and in relation to them the husband of the mother and the wife of the father are vitricus and noverca (step-father and step-mother). In the collateral line the husband’s brother is levir (brother-in-law), the husband’s sister is glos (sister-in-law). Intermarriage with affines in the direct line, or their ascendents or descendents, was absolutely prohibited; collateral alliance appears to have been no impediment in the time of Gaius, but at a later period marriage with a deceased brother’s wife or a deceased wife’s sister was forbidden, Cod. Theod. 2, 3, 12; Cod. 5, 5, 5.
To the marriage of a filius- or filia-familias the consent of the father was required: but if he withheld it without a reason he could be compelled by the magistrate to give it, and, in the case of a daughter, to provide a dower, Dig. 23, 2, 19: one of several instances in which, as the condition of the validity of a title, when a voluntary action could not be obtained, the legislator substituted a compulsory action, instead of simply declaring the action unnecessary. See § 190, comm.
DE ERRORIS CAVSAE PROBATIONE.
§ 65. It sometimes happens that children when first born are not in their father’s power, but are subsequently brought under it.
§ 66. Thus, under the lex Aelia Sentia a Latin who marries and begets a son of Latin status by a Latin mother, or a citizen of Rome by a Roman mother, has not power over him; but on proof of his case as required by the statute, he becomes a Roman citizen along with his son, who is henceforth subject to his power.
§ 67. Again, if a Roman citizen marry a Latin or an alien woman, in a mistaken belief that she is a Roman citizen, the son whom he begets is not in his power, not indeed being born a Roman citizen, but a Latin or an alien, that is to say. of the same status as his mother, for a child is not born into the condition of his father unless his parents had capacity of civil marriage: but a senatus-consult allows the father to prove a cause of justifiable error, and then the wife and son become Roman citizens, and the son is thenceforth in the power of the father. The same relief is given when a Roman citizen under a like misconception marries a freedwoman having the status of a surrendered foe, except that the wife does not become a Roman citizen.
§ 68. Again, a female Roman citizen who marries an alien, believing him to be a Roman citizen, is permitted to prove a cause of justifiable error, and thereupon her son and husband become Roman citizens, and simultaneously the son becomes subject to the power of his father. Similar relief is given if she marry an alien as a Latin intending to comply with the conditions of the lex Aelia Sentia, for this case is specially provided for in the senatus consult. Similar relief is given to a certain extent if she marry a freedman having the status of a surrendered foe instead of a Roman citizen, or instead of a Latin, whom she intended to marry according to the provision of the lex Aelia Sentia, except that the freedman husband continues of the same status, and therefore the son. though he becomes a Roman citizen, does not fall under paternal power.
§ 69. Also a Latin freedwoman married according to the provision of the lex Aelia Sentia to an alien whom she believed to be a Latin, is permitted by the senatusconsult, on the birth of a son, to prove a cause of justifiable error, and thereupon they all become Roman citizens, and the son becomes subject to paternal power.
§ 70. Exactly the same relief is given if a Latin freedman mistakenly marry an alien woman believing her to be a Latin freedwoman, or a Roman citizen, when he intended to comply with the lex Aelia Sentia.
§ 71. Further, a Roman citizen who marries a Latin freedwoman, believing himself to be a Latin, is permitted on the birth of a son to prove the cause of his mistake as if he had married according to the provisions of the lex Aelia Sentia. So, too, a Roman citizen, who marries an alien, believing himself to be an alien, is permitted by the senatusconsult on the birth of a son to prove the cause of the mistake, and then the alien wife becomes a Roman citizen, and the son becomes a Roman citizen and subject to the power of the father.
§ 72. Whatever has been said of a son applies to a daughter.
§ 73. And as to the proof of the cause of error, the age of the son or daughter is immaterial, except that, if the marriage was contracted with an intention to satisfy the requirements of the lex Aelia Sentia, the child must be a year old before the cause can be proved. I am aware that a rescript of the late Emperor Hadrian speaks as if it was a condition of proof of the cause of error that the son must be a year old, but this is to be explained by the particular circumstances of the case in which this rescript was granted.
§ 74. It is a question whether an alien, who has married a Roman wife, can prove cause of error under the S. C. But when an alien, believed to be a Roman citizen, married a Roman wife, and subsequently to the birth of a son acquired Roman citizenship, on the question arising whether he could prove the cause of error, a rescript of Antoninus Pius decided that he was just as competent to prove as if he had continued an alien: from which may be gathered that an alien is competent to prove the cause of error.
§ 75. Hence it appears that a person born in marriage is an alien if his father was a Roman citizen and his mother an alien, or if his father was an alien and his mother a Roman citizen, though if the marriage was contracted under a mistake, a remedy is supplied by the S. C. as above explained. No relief is given in any case, where the parties did not contract marriage under an error, but were aware of their condition.
Mistake or error sometimes conferred a right which a party could not have acquired if he had not acted under a mistake. Thus, the lender of money to a filiusfamilias without the father’s consent had no legal claim to recover, unless he lent believing the borrower to be independent (sui juris), and possession could not mature by usucapion into ownership, unless it had a bona fide inception, i. e. unless it commenced in an honest misunderstanding. The relief of error had similarly important results in questions of status. Erroris causam probare seems to mean ‘to make good a title by error,’ i. e. to establish, as title (causa) to relief, a probabilis error or justa ignorantia; i. e. a mistake not due to negligence; for negligence would exclude from relief.
The subjection of a child to patria potestas by erroris causae probatio operated to invalidate a previously executed will, like the subsequent birth (agnatio) of a child in civil wedlock (suus postumus), 2 § 142.
DE STATV LIBERORVM.
§ 76. It is to be remembered that we are speaking of a marriage between persons who have not the capacity of entering into a civil