Usucaption

Usucaption (Latin usucapio) (in U.S. and U.K. known as acquisitive prescription) is a concept found in civil law systems and has its origin in the Roman law of property.

Usucaption is a method by which ownership of property (i.e. title to the property) can be gained by possession of it beyond the lapse of a certain period of time (acquiescence). While usucaption has been compared with adverse possession (that is, squatting), the true effect of usucaption is to remedy defects in title.

The necessity for usucapion arose in Roman law with the divide between res mancipi and res nec mancipi. Res mancipi required elaborate and inconvenient formal methods of conveyance to transfer title (a formal mancipatio ceremony, or in iure cessio).Res nec manicipi could be transferred by traditio (delivery) or in iure cessio.

The remaining form of conveyance was traditio. This was an informal conveyance which required only an intention to transfer and delivery of the property. If res mancipi were transferred by traditio, full ownership would not pass and the recipient would become a bonitary owner.

Therefore another form of conveyance was required that did not necessitate a ceremony or appearance before the praetor. Because Rome was becoming mercantile, it was simply inconvenient to perform a formal conveyance simply because property was classed as res mancipi. There might also be a demand to transfer property in private between the transferring parties, such as in the establishment of fideicommissa (Roman trusts).

...
Wikipedia