The practice of public notary offices is that while writing document of contracts advocacy, a letter of confess is written regarding conclusion of an irrevocable and disclaimer of right to terminate advocacy. There will be no details of this contract for the third parties. It is a well established and common practice. However, when the cancellation of such clause is claimed, the first court while investigating the common custom, may establish the non conclusion of an irrevocable. At the end it may rule the invalidity of such caluse. This rulling may be confirmed by the appeal court. The courts consider such clause as one wich is not descriptive. For this reason they accept the cancellation of such clause. However this clause is of descriptive character. So the best way is to establish that such clause is not true. In this article, according to the decision of the court, the validity of this condition is discussed. It seams thatin accordance withthe principle offreedom of contract, the legal system should follow thereal intent of the parties to the contract.