This article assumes a broad notion of object in order to propose the recognition of a supervening unlawful object exception as a specific ground of contractual ineffectiveness in the event of possible contraventions of the public economic order. The general theory of contract must consider that certain obligations may become impossible to perform due to the existence of a supervening unlawful object. Public order and especially economic order are limitations to the autonomy of the will and to the binding force of contract. Thus, public order may affect pacta sunt servanda and the intangibility of contracts, since no one is bound to what is unlawful.