(Ref: John Bouvier, A Law Dictionary Adapted to the Constitution and Laws of the United States of America and the Several States of the American Union, Childs & Peterson, c1856.)

MANCIPATIO, civil law. The act of transferring things called res mancipi. (q.v.) This is effected in the presence of not less than five witnesses, who must be Roman citizens and of the age of puberty, and also in the presence of another person of the same condition, who holds a pair of brazen scales, and hence is called Libripens. The purchaser (qui mancipio accipit) taking hold of the thing, says I affirm that this slave (homo) is mine, ex jure quiritium, and he is purchased by me with this piece of money (sas) and brazen scales. He then strikes the scales with the piece of money and gives it to the seller as a symbol of the price (quasi pretii loco.) The purchaser or person to whom the mancipatio was made did not acquire the possession of the mancipatio; for the acquisition of possession was a separate act.Gaius. 1, 119; Id. iv. 181. Both mancipatio and in jure cessio existed before the twelve tables. Frag. Vat. 50. Mancipation no longer existed in the code of Justinian, who took away all distinction between res mancipi and nec mancipi. Smith's Dict. Gr. & Rom. Antiq. Verb. Mancipium; Coop. Jus. 442.