An instrument (muḥarrar) is among the most important means of proof in litigation, as it may create substantial financial or legal obligations and may be the decisive factor tipping the balance in favour of one litigant before the court. For this reason, the Saudi Law of Evidence devoted special care to regulating instruments, drawing a clear distinction between the official instrument and the ordinary instrument in terms of definition, evidentiary force, and legal effect.
The official instrument is one in which a public officer, or a person charged with a public service, records what was done by them or what they received from the concerned parties, in accordance with legal formalities and within the limits of their authority and jurisdiction. The Law of Evidence granted such instruments special force: Article 26 provides that the official instrument is conclusive against all (ḥujja ʿalā al-kāffa) as to the matters its author performed within the scope of their task, or that occurred in their presence from the concerned parties, unless its forgery is established by the means prescribed by law. Consequently, the official instrument is conclusive proof; whoever relies on it need not prove its validity, and it can only be challenged through a forgery claim following the prescribed legal procedures.
The ordinary instrument is what the parties draw up between themselves — including contracts, acknowledgements, and all instruments that do not meet the conditions the Law set for the official instrument; legally it is deemed an ordinary instrument. The Law of Evidence regulated its authority in Article 29, which provides that the ordinary instrument is proof against the one who signed it, unless they expressly deny the handwriting, signature, seal, or fingerprint attributed to them. If the signature is established, the signatory is bound by everything stated in the instrument, and may not thereafter claim lack of understanding, haste, or ignorance of its content. Whoever is confronted with an ordinary instrument and discusses its substance before the court may not subsequently deny its validity.
It is thus clear that the ordinary instrument, despite its apparent simplicity, may create a complete legal obligation once its attribution to its signatory is established, and denying it may entail complex proof procedures and legal consequences that prolong the dispute. Hence, the real difference between the official and the ordinary instrument does not appear at the moment of signing, but becomes evident when a dispute arises and the parties appear before the court, where the evidentiary force of each instrument — and its effect in proving rights or not — is determined.