ACCESSIONE. — Accession may be defined as an original mode of acquiring ownership through the incorporation or addition to one’s own property of an asset that did not form part of it and was not under one’s dominion. This right is not conferred by nature, but rather sanctioned by positive laws.
The great moralists applied to this institution, for the most part, the principles of Roman law, which had become common law and which, in this matter, had undergone a long and meticulous elaboration. Today it is necessary to apply the civil law of each nation, even when ecclesiastical goods are concerned (cf., by analogy, can. 1526), subject to the principles of divine and canon law.
Accession raises no particular questions of law or morality when the things belong to the same owner, or when different owners arrange the incorporation of the things by mutual agreement: in that case, it is sufficient to abide by the contract. When, on the other hand, there is no agreement among the different owners, it is necessary to have recourse to the provisions of civil law, which are substantially based on the principle of equity and adopt prevalence as their criterion: accessorium cedit principali.
The principal thing is that to which the other is subordinate. If one of the things is immovable and the other movable, the latter is accessory and the former principal; if both are movable, the ranking is generally determined on the basis of their purpose or, in the absence of other elements, on the basis of their value. But the owner of the principal thing is required to reimburse the other to the extent of the enrichment; indeed, if he brought about the accession in bad faith, he is also required to compensate for the damage.
Accession through fructification, of which almost all moralists speak, has no place in Italian law, which, returning to the concept of Roman law, speaks of this intrinsic expansion or development of ownership where it deals with fruits (Cod. Civ. It., arts. 820–21), not classifying it among the modes of acquiring ownership (I. III tit. II, cap. 111). In accession, as it now exists in Italian law, the extension of ownership does not proceed through the intrinsic expansion of the thing, but rather expands by virtue of a new title, created through the occurrence of a new legal fact.
There are various ways in which accession thus conceived may occur. If the various cases are reduced to a certain unity, one may speak of two classes of accession, according as the matter concerns immovable things among themselves and in relation to movable things, or movable things among themselves; alternatively, the classification may be made according as the fact of union is chiefly the work of nature or human industry is the principal factor. Following the first scheme of classification, the following forms belong to the first category of accession (between immovable things or between movable things and immovables): alluvion, avulsion, new island, and abandoned riverbed, in which the work of nature predominates; and building and planting, in which human labor predominates over the work of nature. The second category (accession between movable things) includes union, commingling, specification, etc., in which human industry again predominates.
1. — Under the name of alluvion are included the unions of earth and the accretions that form successively and imperceptibly (incrementum latens) on land situated along the banks of rivers or torrents (Cod. Civ. It., art. 941). Avulsion occurs when a river or torrent, through an instantaneous force, detaches a considerable and recognizable part (incrementum patens) of land adjoining its course and carries it toward a lower parcel of land or toward the opposite bank. In both cases, the owner of the land also becomes the owner of the earth added to it, except where the alluvion results from the regulation of the river’s course, from land reclamation, or from other similar causes (arts. 941, 947), and subject, in the case of avulsion, to compensation payable to the other owner within the limits of the increase in value brought to the enlarged land by the avulsion (art. 944).
A different rule applies when avulsion gives rise to a new island in the riverbed: the owner of the land from which the detachment occurred retains ownership of II. The same rule is observed when the island is formed not by avulsion strictly speaking, but by the new course of a river or torrent that crosses and surrounds the land, or part of the land, of an adjoining owner (art. 945). Apart from these two cases, all other islands and unions of earth formed in the beds of rivers or torrents belong to the public domain (art. 945). However, the rules concerning islands and unions of earth do not apply when the change in the riverbed results from regulation of its course, land reclamation, or other similar causes (art. 947).
If a river or torrent forms a new bed, abandoning the old one, the abandoned riverbed belongs to the owners adjoining the two banks. They divide it as far as the middle of the bed itself, according to the extent of the frontage of each owner’s land (art. 946). If, instead of changing its bed, the river or torrent imperceptibly moves away from one of the banks and shifts toward the other, the land abandoned by the water belongs to the owner of the uncovered bank, without the adjoining owner on the opposite bank being able to claim the lost land, natura enim contingit (art. 942). But if human intervention is involved through regulation of the course of rivers, land reclamation, and so forth, the foregoing rules do not apply (art. 947).
Building — Planting — New Works. — As a general rule, any planting, construction, or work carried out above or below the soil belongs to the owner of the soil (art. 934), according to the classical principle: Quidquid plantatur, seritur vel inaedificatur, totum solo cedit, radices si tamen egit. It is nevertheless necessary to bear in mind the particular rules that civil law lays down for the various possible situations, in relation to ownership of the material used in the construction and similar matters, and to the right and duty of compensation (arts. 934–38).
2. — Between movable things, accession may occur in an indefinite series of cases, which the legislator cannot contemplate all individually. Italian legislation deals with three principal cases: union, commingling (or mixing), and specification.
In union and commingling, the different things, although forming a single body, remain substantially distinct, as in writing, painting, weaving, alloys of metals, etc. Since each person retains ownership of his own thing, he has the right to obtain its separation, if possible; otherwise, there is common ownership in proportion to the value of the things belonging to each. But if one of the things has a much greater value, or may be regarded as the principal thing, its owner acquires ownership of the whole, while remaining obliged to pay the other or others the value of their thing, or, if the union occurred without his consent, the lesser sum between the increase in value brought to the principal thing and the value of the accessory thing, without prejudice to the right to compensation for damages in the event of gross negligence (art. 939).
Specification is the accession of a new form to pre-existing material, so as to give body to a new thing, a new species. If someone has used material that did not belong to him to form a new thing, whether or not the material can be restored to its original form, he acquires ownership of it by paying the owner the price of the material, unless the value of the material considerably exceeds that of the labor; in that case, the positions are reversed (art. 940).