Modes of Adoption
As in the case of arrogation, there was an earlier ceremonial form of adoption which was superseded in later times by an informal mode. Unlike arrogation, however, adoption could be effected by private act. To effect an adoption required two distinct steps : first, the extinction of the former patria potestas, which was accomplished by the ceremony of emancipation (by the father selling his son three times into bondage) , and, second, the establishment of the new patria potestas, which was accomplished by a fictitious suit in which the adopter claimed the son as his.
In the case of the adoption of a daughter or grandchild, a single sale was sufficient to extinguish the original patria potestas. In Justinian's time, the adoption was accomplished by a simple declaration before a magistrate recorded in writing. The assent of the adopted person was not required.