Mancipium

The power acquired over a freeman by the mancipatio. To form a clear conception of the true import of the word in the Roman jurisprudence, it is necessary to advert to the four distinct powers which were exercised by the pater-familias, viz.: The manus, or marital power; the mancipium, resulting from the mancipatio, or alienatio per aes et libram, of a freeman; the dominica potestas, the power of the master over his slaves, and the patria potestas, the paternal power. When the pater-familias sold his son, venum dare, mancipare, the paternal power was succeeded by the mancipium, or the power acquired by the purchaser over the person whom he held in mancipio, and whose condition was assimilated to that of a slave. What is most remarkable is that, on the emancipation from the mancipium, he fell back into the paternal power, which was not entirely exhausted until he had been sold three times by the pater-familias. Si pater filium ter venum duit, filius a patre liber esto. Gaius speaks of the mancipatio as imaginaria quaedam venditio, because in his time it was only resorted to for the purpose of adoption or emancipation.

See "Adoption;" "Pater-Familias;" 1 Ortolan, 112 et seq.