Apart from the derivative methods of transfer of ownership, requiring involvement from the previous owner (mancipation, in iure cessio, tradition), there were also primary methods recognised in the Roman law. Appropriation, accession, modification, acquisition of property from utilities, discovery of a treasure and usucaption all belong to this category. These methods were independent of the previous owner’s rights.
Appropriation meant taking possession of nobody’s thing with the intention of keeping it for oneself. According to the res nullus cedit primo occupanti rule, a thing that belonged to nobody became the property of the first one to claim it. Things that could be appropriated included everything that could be captured on land, sea and in the air – omnia, quae terra, mari, caelo capinatur. Moreover, things that could be appropriated encompassed also things thrown ashore by the sea (seashells, stones), islands emerged from the sea, things abandoned by their owner (intention to get rid of the property was required) as well as properties belonging to an enemy found on Roman soil at the time of a war outbreak.
Accession was invoked when ownership of a side thing was acquired through its permanent connection with the main thing in such a way that the side thing became a part of the main thing. Connecting immobile things with immobile things, mobile things with immobile things and mobile things with mobile things all fell in this category. An example for the first case was alluvium (expansion of land through accumulation of river material at the expense of some other land) and detachment (sudden separation of a piece of land and its eventual connection to some other land) as well as islands emerged on rivers. Examples of the second case included building and planting, according to the superfices solo cedit – things on the land are connected to the land. The third case comprised of ferruminatio – connecting things made from the same metal, plumbatio – connecting things with the use of a different metal, confusio – mixing various liquids, commixtio – mixing of solid bodies. If things could not be separated, a joint ownership was created in which shares were proportional to the input of every co-owner. Money were an exception, when mixed they became the sole property of the owner.
Modification of things (specificatio) meant processing of somebody else’s material without that person’s consent – for example making wine from grapes, a ship from wood, a bread from flour, fabric from yarn or a vessel from metal. With time, two schools emerged – the Sabinians held that the ownership of the newly created thing belongs to the owner of the material used while the Proculians believed that it should belong to the manufacturer, arguing it the new thing is appropriated as previously belonging to nobody. The middle ground presented by Paulus was accepted and incorporated by Justinian. According to Paulus, if it was possible to reverse the thing to the original state, the owner of the material was the owner and the manufacturer could make claims on the basis of the performed work. If however it was not possible, then the manufacturer was the owner of the new thing, provided he acted in good faith, and the owner of the material could make claims on the basis of lost material.
Acquisition of the property from utilities happened for the owner of the main thing, the holder in good faith and the lease holder at the moment of separation of utilities from the main thing (separatio). Also a user could acquire property from utilities at the time of collecting utilities (perceptio). On the other hand a tenant could acquire utilities in a derivative way, with the consent of the owner, but also with the use of perceptio.
A treasure (thesaurus) was a fortune hidden so long ago that all memory of its owner had been lost. Such a treasure found on one’s land belonged to the owner of the land. Originally it was treated as a part of the estate, only Justinian’s reforms caused a treasure found on somebody else’s land to be split between the land owner and the finder. The concept of treasure was not applied to the spoils of war which belonged to the state (it was possible to transfer them into private hands at a later time by the appropriate state authorities).
Usucaption or acquisitive prescription (usucapio) was acquisition of property through continuous ownership for a given time. It was not possible to gain property of things excluded from circulation, provincial lands, escaped slaves, stolen things and state properties in this way. There were two types of usucaption: usucapio and longi temporis praescriptio. The first emerged from the old ius civile and was available only for the citizens; it required a legitimate claim to ownership and good faith. For movable things the required time was one year and for immovable things it was two years. The second type was originally a process action in which the holder of the land requested to return it to the owner could defend himself by presenting the claim of long-lasting possession after ten (if the plaintiff and the defendant lived in the same province) or twenty years (the they lived in different provinces). With time usucaption evolved into acquiring property of different things as well. Justinian compiled the two types of usucaption and from his times onwards usucapio was used for usucaption of movable things while longi temporis praescriptio was used for usucaption of immovable things. Also the time requirements were changed – movable things could be acquired after three years and immovable things after ten (new and old owner from the same province) or twenty years (different provinces). After thirty years it was possible to acquire ownership of the lands belonging to the emperor, state and church and a legitimate claim to the ownership (for example inheritance, dowry, purchase), necessary in the other cases, was not required. In general it was also required for the person acquiring property to take possession in his own name and in an uninterrupted way.