Although it may seem contradictory that Uruguayan law allows someone who is not the owner to acquire title through the mere passage of time, acquisitive prescription (adverse possession, or usucaption) is one of the oldest mechanisms by which the law favors legal certainty over the registered owner's inactivity. It dates back to 450 B.C., when Rome regulated usucapio (usu = use, capere = to take): acquiring through use. This raises the question of whom the law protects — the possessor or the owner — what its rationale is, and what mechanism allows a possessor to become an owner.
Legal function: adverse possession may be seen as a disruptive institution that contradicts Article 32 of the Constitution ("Property is an inviolable right..."), but that article continues: "...but subject to whatever laws may be enacted for reasons of general interest." Adverse possession contributes legal certainty, protects the possessor and reinforces the social function of property. The stability of patrimonial legal relationships ensures that consolidated rights and situations are not altered arbitrarily. The social function implies that the owner has faculties but also duties toward society, an evolution from the purely individualistic nineteenth-century view.
Whom does the law protect? The rules protect the owner against all others, provided the owner exercises over the property the average diligence of a prudent businessperson. There is no automatic loss of a right by abandoning a property, but there are mechanisms through which an owner may lose that right as an indirect consequence of abandonment, through the activity of third parties. As legal scholarship puts it: "the institution operates when the holder of a right over an asset abandons it, or fails to possess it; this opens the possibility for another to possess it and, upon meeting the required term and conditions, become its holder, generally of ownership."
An original mode of acquisition: adverse possession is a mode of acquiring property (Article 705 of the Civil Code: occupation, accession, tradition, succession upon death, and prescription). A distinction is drawn between derivative modes (transmission from a prior legal relationship, e.g., a sale perfected by tradition) and original modes (which consolidate ownership independently of the prior owner, curing defects in title). Adverse possession is an original mode (Article 1211 of the Civil Code: ownership of real property is acquired by twenty years of possession, without the need to produce title and without the possibility of raising a claim of bad faith, except as provided in Article 633).
Elements of qualifying possession: possession requires material apprehension (corpus) plus the intent to hold as owner (animus domini); the possessor perceives themselves as the owner and manifests this through acts. This is distinguished from mere holding: for example, A leases to B; B maintains the property and pays for services but acknowledges A as the owner (a mere holder). If B did not enter with authorization, does not acknowledge A as the owner, and performs such acts for more than one uninterrupted year, B acquires the right of possession (Article 649.3 of the Civil Code). Possession must be (Article 1196 of the Civil Code): continuous and uninterrupted, peaceful, public, unequivocal, and held in the capacity of owner.
Time periods: the passage of time transforms a qualifying possessor into an owner: twenty years for real property and three years for movable property, under Article 463 of the Urgent Consideration Law No. 19,899, which shortened these periods. The required period may be met by a single possessor or built up through the tacking of successive possessions (Article 1206 of the Civil Code), by way of assignment of possessory rights, provided each possession is shown to meet the requirements of Article 1196.
Process and effects: the passage of time operates ipso iure, but enforceability against third parties requires a judicial adverse-possession proceeding (an extraordinary proceeding under Article 346 et seq. of the General Code of Procedure) to achieve registry regularity and public notice. It is essential to prove possession and its duration through a survey plan, tax or municipal clearance, assignments of possessory rights, photographic records, tax regularization, and witness testimony. Once these facts are proven, the declaratory judgment has a dual effect: the registered owner's title ceases, and the possessor becomes the owner.
Conclusion: adverse possession raises the question of whether the right of the person recorded as owner should prevail, or that of the person who, for decades, acted as such. Time, accompanied by qualifying possession and the owner's inactivity, is not a mere chronological fact but an event that generates rights.
Sources. Legal scholarship: Revista CADE, vol. 62 (February 2022); Howard, Walter, Modos de adquirir (University of Montevideo); Bellín, Usucapión (LJU, Vol. 157); Yglesias, Derecho de las cosas, Vol. II, Part 1. Legislation: Uruguayan Civil Code (Law No. 16,603). Case law: Supreme Court of Justice, Judgment No. 61/1993; Second Civil Court of Appeals, Judgment No. 111/2022.
