Nuda pactio obligationem non parit

. aut enim re contrahitur obligatio aut verbis aut litteris aut consensu."^[2612] This was the systematic subdivision upon which Gaius based his exposition of the law of contractual obligations.

We have, by now, made our way through all the four categories mentioned. We have seen that an obligation could arise either on the basis of certain formal arrangements between the parties or by virtue of the real act of handing over an object. One of the most significant achievements of the Roman lawyers was, however, that they were prepared to grant an action even in cases where nothing more than a mere agreement had intervened. These were the consensual contracts. But their number was limited. Only if the (informal) arrangement between the parties could be classified as emptio venditio, locatio conductio, mandatum or societas was it enforceable. This was the numerus clausus of contracts concluded (nudo) consensu. Conversely, then, a mere pactum, that is, an agreement that did not fit into one of these categories, was not actionable: '"nuda pactio obligationem non parit", as Ulpianus put this regula iuris.^[2613] This did not, however, mean that such a pactum—or pactio^[2614]—was entirely ineffective or invalid. "... sed parit excep­tionem" is how Ulpian continues: in the course of the proceedings in iure, the defendant could ask, on the basis of a nudum pactum, for the insertion of an exceptio pacti into the formula. Most notably, an informal release from an obligation could become effective that way ("pactum de non petendo"), but also an agreement, according to which the creditor was not to claim performance for a certain period of time.^[2615] This is what the praetor referred to when he promised: "Pacta conventa... servabo."^[2616] With these words he did not intend to provide a positive sanction in the form of an action. For the protection of the debtor it was sufficient to make available a defence. On account of the pactum he could reasonably expect not to be sued at all, or not to be sued for some time. What he needed, therefore, was an exceptio in case the creditor instituted an action regardless of his promise.

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More on the topic Nuda pactio obligationem non parit:

1. Hypotheca Contracted Nuda Conventione
2. Pacta vestita and pacta nuda
3. The contribution of (commercial) practice
4. 1. Contract and pacta in the Corpus Juris Civilis
5. Roman Law Terms with Letters P
6. Causa in Roman law
7. Actio Serviana and Actiones Pigneraticiae in Personam
8. The concept of impossibility
9. References to the boni mores in classical law
10. 2. The "natural" law of delict
11. Introduction