Facultative Obligation Law and Legal Definition

Facultative obligation refers to a type of obligation where one thing is due, but another is paid in its place. In such type of obligations there is no alternative provided. The debtor is given the right to substitute the thing due with another that is not due.

The following is an example of a case law (Louisiana) differentiating between Facultative obligation and Alternative Obligation:

A difference exists between the alternative obligation and facultative obligation. In the alternative obligation there are two things equally due, under an alternative, it is true duo sunt in obligatione. In the facultative obligation, on the contrary, but one thing is due, unaest in obligatione; the other may be paid in its place, but it is not due, it is only in Facultatesolutionis; from which the name facultative obligation. [Salles v. Stafford, Derbes& Roy, Inc., 17 La. App. 440 (La.App. 1931)]