Consensual contracts

Consensual contracts were those in which a simple agreement was binding. They were all bilateral (but the mandate only imperfectly so) and concluded by formless consent. Consent sufficed of itself (Gaius 3.136): no transfer of the item or symbolic act was required.

Classical Roman law recognized four consensual contracts: sale (emptio venditio), hire (locatio conductio), partnership (societas), and mandate (manda­tum). All consensual contracts were based on good faith, and this foundation in good faith allowed the contracting parties a greater degree of flexibility in defining the content of their obligations. On the other hand, these arrangements gave the judge wide discretion in taking into account particular circumstances in case of conflict between the parties.

Sale (emptio venditio)

The sale was the most important of all consensual contracts. It was the contract by means of which goods were exchanged for money. A sale was concluded when the buyer and the seller agreed by formless consent upon the thing to be sold and the price to be paid for it.

The sale by itself did not transfer ownership: mancipation, in iure cessio, or traditio was required. Sale was, therefore, neither a conveyance nor a contract for transferring ownership, which remained strictly separate. Consequently, the sale of a thing not belonging to the seller could be valid. Similarly, payment of the price was not a condition for the passing of ownership. However, until the buyer paid the price, he was not entitled to bring contractual action (actio empti) against the seller.

The object of a sale could be anything not legally excluded from private transaction (Paul, D. 18.1.34.1). Noncorporeal things and rights (e.g., servitudes, inheritance) and even future things could be sold - e.g., the sale of next year’s crop or the unborn child of a slave woman. The use of land or the labor of workers could not be sold, however.

The price of a sale had to be money. In classical law, parties were free to fix the price, but it had to be certain (certum) and real (verum). Certainty required only that the price could be at least indirectly identified (e.g., “what you paid for it”). “Reality” meant that the price had to be genuine, authentic, though its adequacy with an objective value was irrelevant. Postclassical and Justinian laws, however, limited the parties’ freedom to establish a price.

Two main obligations arose from a sale: (a) the seller’s obligation to deliver the free and undisturbed possession of the thing (vacua possessio) to the buyer, and (b) the buyer’s obligation to pay the price. These two obligations were intrinsically connected. If the thing perished by accident after the con­clusion of the sale, the buyer assumed the risk (periculum est emptoris) and had to pay the price. The seller, however, was liable for safekeeping (custodia), for instance, in case the thing was stolen before the delivery. Both the seller and buyer were liable for fraud (dolus) and negligence (culpa). The seller had the actio venditi against the buyer who did not pay the established price at the fixed time; the buyer, on the other hand, had the actio empti to force the seller to deliver the thing.