Res mancipi

In Roman Law. Those things which might be sold and alienated, or of which the property might be transferred from one person to another. The division of things into res mancipi and res nec mancipi was one of ancient origin, and it continued to a late period in the empire. Res Mancipi (Ulp. Frag, xix.) are prce dia in italico solo, both rustic and urban; also, jura rusticorum pradiorum or servitutes, as via, iter, aquceductus; also slaves, and four-footed animals, as oxen, horses, etc., qucc collo dorsove domantur. Smith, Diet. Gr. & Rom. Antiq. To this list may be added children of Roman parents, who were, according to the old law, res mancipi. The distinction between res mancipi and nec mancipi was abolished by Justinian in his Code. Id.; Cooper, Inst. 442. RES NOVA (Lat.). Something new; something not before decided. RES NULLIUS (Lat.). A thing which has no owner. A thing which has been abandoned by its owner is as much res nullius as if it had never belonged to any one. Also things which are not the subject of private ownership. The first possessor of such a thing becomes the owner; 7'es nullius fit primi occupantis. Bowy. Com. 97.

In Roman law. Certain classes of things which could not be aliened or transferred except by means of a certain formal ceremony of conveyance called "mancipatio," (q. vt) These included land, houses, slaves, horses, and cattle. All other things were calied "res nec mancipi-" The distinction was abolished by Justinian.
—

Defined under Res in Black's Law Dictionary.