Liability for renunciation of a legal act in a contract has been less discussed in Iranian civic rights; yet it is a controversial subject for jurisprudents, and subsequently for the jurists. Three opinions can be considered when a legal act in a contract is supposed to be renounced - due to a condition - but is not whatsoever. First, while the conditioned legal act is considered to be lawful, the party being conditioned to do or not do still keeps the right to renounce it. Second, if the legal act is in contradiction to the condition of renouncing the conditioned one, thus it would be unlawful. And third, if the legal act is against the condition, it would be irrelevant. The authors try to examine various proofs brought by jurisprudents and the jurists and they decide the second of the above opinions seems to be more defensible.