In Late Antiquity, private individuals could acquire land or other assets through acts of the emperor or the administration. These often originated from confiscations, e.g. of estates without heirs (bona vacantia, caduca), the property of convicted criminals (bona damnatorum), or ownerless slaves (vaga mancipia). Since the fiscus was often unable to make economically effective use of these assets, and the emperor was under political pressure to reward influential individuals, they were frequently transferred - sometimes for payment, but often free of charge. In this context, a procedure developed whereby beneficiaries could petition for an imperial grant by means of a petitio. By analysing Late Antique imperial constitutions, the study examines this procedure, as well as the private-law status of the recipients. The analysis shows that they generally acquired ownership - even where the assets had not belonged to the fiscus. As Roman law in principle did not allow acquisition in good faith from a non-owner, this form of acquisition is best understood as one effected by sovereign act. At the same time, it becomes clear that Late Antique emperors established nuanced and carefully considered rules and sought to achieve a fair balance of interests. A decline in legal culture, as suggested by the theory of so-called Late Antique vulgar law, cannot be observed.