Roman retention of title clauses as retention of possession. It is the dominant view that Roman law did not know retention of title clauses (pactum reservati dominii) which is, accordingly, considered to be an invention of the medieval ius commune. This opinion is true to the extent that retention of title was inefficient from the Roman point of view because the buyer as possessor was always in the position of acquiring ownership by acquisitive prescription (usucapio), the requirement of good faith being met in these instances. The Roman lawyers, therefore, devised different means to make sure that the buyer would get the use of the sold good (detentio) without becoming possessor thus preventing the dreaded usucapio. This 'retention of possession' (Besitzvorbehalt) is the Roman functional equivalent to modern retention of title.