40 Evidence Cap 80 [2009] a document, have been proved according to section 97, no evidence of any oral agreement or statement shall be admitted as between the parties to any such instrument or their representatives in interest for the purpose of contradicting, varying, adding to or subtracting from its terms: Provided that (i) any fact may be proved which would invalidate any document, or which would entitle any person to any decree or order relating thereto; such as fraud, intimidation, illegality, want of due execution, want of capacity in any contracting party, want or failure of consideration, or mistake in fact or law; (ii) the existence of any separate oral agreement as to any matter on which a document is silent, and which is not inconsistent with its terms, may be proved, and in considering whether or not this paragraph of this proviso applies, the court shall have regard to the degree of formality of the document; (iii) the existence of any separate oral agreement constituting a condition precedent to the attaching of any obligation under any such contract, grant or disposition of property may be proved; (iv) the existence of any distinct subsequent oral agreement to rescind or modify any such contract, grant or disposition of property may be proved, except in cases in which such contract, grant or disposition of property is by law required to be in writing, or has been registered according to the law in force for the time being as to the registration of such documents; (v) any usage or custom by which incidents not expressly mentioned in any contract are usually annexed to contracts of that description may be proved, if the annexing of such incident would not be repugnant to, or inconsistent with, the express terms of the contract; (vi) any fact may be proved which shows in what manner the language of a document is related to existing facts. Evidence to explain a patent ambiguity. 99. When the language used in a document is on the face of it ambiguous or defective, evidence may not be given of facts which would show its meaning or supply its defects. www.kenyalaw.org