The document can be regarded as the most important and common evidence of parties’ allegations in civil actions and non-criminal affairs. The document presented as evidence may, in some circumstances, conflict with other evidence available at the proceedings, including testimony. In this case, the court must, according to the circumstances, prefer either the document or the competing evidence from among the two conflicting pieces of evidence and judge on its basis. The ruling on the conflict between a deed or authorized document and testimony had been specified in Article 1309 of the Civil Code. However, the Council of Guardians declared this article contrary to Islamic jurisprudence and, in effect, nullified it. Nevertheless, the generally logical assurance arising from a deed or authorized document is stronger than the assurance originating from testimony, and consequently, it seems preferable to consider the deed or authorized document prevailing over testimony in the case of conflict between these evidences, since the occurrence of mistake and forgetfulness is potentially possible in testimony, while there is no such possibility in a deed or authorized document.