Article 1356

Contracts shall be obligatory, in whatever form they may have been entered into, provided all the essential requisites for their validity are present. However, when the law requires that a contract be in some form in order that it may be valid or enforceable, or that a contract be proved in a certain way, that requirement is absolute and indispensable. In such cases, the right of the parties stated in the following article cannot be exercised. (1278a)