Section — Noldin, Summa of Moral Theology
Section 13. Legal Relationship.
604. Nature of the Impediment. 1. The impediment of legal relationship (Burgerliche Verwandtschaft) consists in this, that between persons who have contracted relationship from adoption, valid matrimony cannot be entered.
For the declaration of this matter, see above n. 543.
The impediment of legal relationship is merely of ecclesiastical law. The chief reason for establishing this impediment is the peculiar relation of reverence and friendship which arises from adoption between the adopter and the adopted person. To this is added another reason, namely, to avoid the danger of fornication which would threaten between persons staying in the same family if hope of matrimony shone upon them.
Hitherto the diriment impediment of legal relationship had force in those places in which the law of adoption, with regard to substantial things, agreed with the adoption of Roman law. But this happened from an authentic declaration of the Holy See in France and in the Neapolitan kingdom, and from the interpretation of authors in Germany, Italy, Spain, and in several republics of Latin America. Therefore in these places legal relationship constituted a diriment impediment up to May 19, 1918.
The new Code establishes that legal relationship dirimently impedes matrimony where by civil law it dirimently impedes matrimony.1 Therefore in judging this impediment, one must no longer attend to Roman law, but to the recent law of each state. From the modern codes legal relationship is a diriment impediment in Croatia, Slavonia, Italy, Spain, Poland. In Germany legal relationship impedes matrimony, but does not dirimently impede it.2
In this impediment, as we warned above, the matter of the law is taken from the civil code; the form of the law, or the force of obliging, descends from ecclesiastical law. We have a civil law canonized by the Church.
1 Cn. 1080.
2 Cf. Chelodi, n. 107 s.