Book III: Different ways of acquiring property

The essential qualities of the performance are those which have been expressly or tacitly agreed and in consideration of which the parties have contracted. Error is a cause of nullity whether it relates to the performance of one party or the other. Acceptance of a hazard as to a quality of the performance excludes error relating to that quality.

Mistake as to the essential qualities of the co-contractor is a ground of nullity only in contracts concluded in consideration of the person.

A mistake as to a mere motive, extraneous to the essential qualities of the performance due or of the co-contractor, is not a ground of nullity, unless the parties have expressly made it a decisive element of their consent. Nevertheless, a mistake as to the reason for a liberality, in the absence of which its author would not have disposed, is a cause of nullity.

An error as to value, whereby a contracting party, without being mistaken as to the essential qualities of the service, merely makes an inaccurate economic assessment of it, is not a ground for nullity.

Larceny is when a contracting party obtains the consent of the other by deceit or falsehood. Larceny is also constituted by the intentional concealment by one of the contracting parties of information which he knows to be decisive for the other party. However, it does not constitute fraud for a party not to reveal to his co-contracting party his estimate of the value of the performance.

Larceny is also constituted if it emanates from the contracting party’s representative, business manager, servant or surety. It is also constituted when it emanates from a third party in collusion.

An error resulting from fraud is always excusable; it is a cause of nullity even if it relates to the value of the service or to a simple reason in the contract.

Violence occurs when a party enters into a commitment under the pressure of a constraint which inspires him with the fear of exposing his person, his fortune or those of his relatives to considerable harm.

The threat of legal action does not constitute violence. The situation is different where the legal remedy is diverted from its purpose or where it is invoked or exercised to obtain a manifestly excessive advantage.

Violence is a ground for nullity whether it is perpetrated by a party or by a third party.