Oportet

I. It behooves; it is needful or necessary. Oportet quod certa res dedu Catur in donationem: it is necessary that a certain thing be brought into the gift, or made the subject of the conveycpurt; that is, made the subject of an action, or of the action of the court in the particular case. Oportet quod certa sit res quae venditor: it is necessary that there should be a certain thing which is sold.