Rules of Court
Section 8. How to contest such documents. - When an action or defense is founded upon a written instrument, copied in or attached to the corresponding pleading as provided in the preceding section, the genuineness and due execution of the instrument shall be deemed admitted unless the adverse party, under oath specifically denies them, and sets forth what he claims to be the facts, but the requirement of an oath does not apply when the adverse party does not appear to be a party to the instrument or when compliance with an order for an inspection of the original instrument is refused. (8a)