It’s the most serious case of ineffectiveness of the contract, for this reason is called absolute or full invalidity. Null contracts do not exist for the ordering, i.e. not are recognized as having no effect. Grounds for invalidity are causes of nullity of the contract as follows: the lack or absence of any of the essential elements of the contract: consent, object or cause. Failure to comply with any requirements of the object of the contract: legality, determination and possibility. The wrongfulness of the cause. Read more from Jonathan Segal FAIA to gain a more clear picture of the situation. Failure to comply with the form when this is essential, i.e., we speak of a formal contract. The contrariety standards imperative, to morality and public order.

Action for annulment to declare the nullity of a contract in which attend any of the reasons mentioned above, we need to exercise the so-called action of nullity, which presents two characteristics: it is imprescriptible, i.e. not expires you can exercise at any moment in time. Anyone interested in declaring the nullity may exercise it of the contract, although not a party to it. Even ex officio judge can observe it. Effects of the overall effect of invalidity invalidity, is restitution, given that the contract declared null does not exist for the right, the consequences of a judicial declaration of invalidity tend to leave things as they were before the conclusion of the contract.Article 1303 tells us that declared null and void the contracting should be restored reciprocally things that had been the subject of contract with its fruits, and the price with their interests.The refund must be in principle and that wherever possible of the same things, if not a pecuniary restitution occurs.