Since mancipatio and in iure cessio were inherently public modes of acquisition of ownership, usucapio was the only private method of the ius civile.
These included stolen things, the res mancipi under another's guardianship, and limes – five-foot strips required between adjoining land holdings.
[5] The time period would have formed the prohibitive part in early Rome, where the community was sufficiently small that the owner could easily identify and regain his goods – considering also that if they had been stolen, they could not be usucapted.
This has to be in fact; it cannot rest on a mistaken belief in there being a sale or gift, which is the main difference between iusta causa and good faith in practice.
The bad faith had to be shown at the point of the iusta causa – it was insufficient to show that the claimant later realised that the item had come from a non-owner.
In either case (theft or force) it is only if the owner from whom it has been stolen regains it, or considers it lost forever (i.e. abandons it), that a valid usucapio can take place.
Given this strict limitation, usucapio must surely only have been about shifting the burden of proof to the claimant from the possessor, whose possession was usually easy to show.
[13] To deny the owner the right of vindicatio against the good faith possessor would run contrary to the concept of the usucapio, with it effectively completed before the required time had passed.
It was typical of the Praetor to ignore technical formalities to achieve practical benefits, in this case certainty of ownership.
[13] If either the bonitary owner or good faith possessor was dis-possessed, he could under the normal law claim a possessory interdict against his dis-possessor, but this did not cover further people if possession had been further transferred.
However, the position as to the good faith possessor relied on a concept of relative title, part of the common law, but something which was alien to Roman ideas of ownership.