Civiliter vel naturaliter possidere

The aim of the investigation is to clarify the meaning of the expressions ‘possessio civilis’ and ‘possessio naturalis’ in Roman legal sources. According to the author, possessio civilis was any possession that the ius civile (understood as a system including the ius gentium) deemed to be suitable for founding the purchase (immediate or through usucapio) of the dominium ex iure Quiritium with reference to the existence of three fundamental conditions, and in particular in that: a) headed by subjects who colud be holders of the dominium ex iure Quiritium; b) concerning things that could be acquired in civil property; c) qualified by a title able to justify the purchase of the civil property. Any possession thath lacked any of these three requirements was instead a possessio naturalis and was therefore considered by the ius civile as a mere factual situation, without consideration of whether or not it was protected by the normal interdicta in defense of possession. So, the author contests the dominant opinion (still represented today by Riccobono) that possessio naturalis would have been a mere detention for classical jurists. In the end, the author highlights that the expression possessio naturalis was also used to designate the detention as a costitutive element of possession and he argues that every possessio, including possessio civilis, was naturalis as it consisted of a relationship of fact between man and thing. Threrefore the possessio naturalis, in his opinion, should constitute the basis and the starting point for a correct approach to the Roman theory of possession.