LEGAL PRINCIPLE: EVIDENCE LAW – Admissibility of Oral Evidence – Written Contracts
PRINCIPLE STATEMENT
Oral evidence on contractual terms offends section 132(1) of the Evidence Act which provides that when any contract has been reduced to the form of a document, no evidence may be given of the terms of such contract except the document itself or secondary evidence of its contents in cases where secondary evidence is admissible; nor may the contents of any such document be contradicted, altered, added to or varied by oral evidence.
RATIO DECIDENDI (SOURCE)
"The said oral evidence on the rate of interest offends section 132(1) of the Evidence Act Cap. 112 Laws of the Federation of Nigeria, 1990 which provides: 'When any judgment of any court or any other judicial or official proceedings or any contract, or any grant or other disposition of property has been reduced to the form of a document or series of documents, no evidence may be given of such judgment or proceedings, or of the terms of such contract, grant or disposition of property except the document itself, or secondary evidence of its contents in cases in which secondary evidence is admissible under the provisions herein before contained; nor may the contents of any such document be contradicted, altered, added to or varied by oral evidence.'"
EXPLANATION / SCOPE
Section 132(1) Evidence Act codifies the parol evidence rule (see Principle 422) and best evidence rule. For documentary contracts: Primary evidence: the document itself must be produced. Secondary evidence: permitted only when primary evidence is unavailable (lost, destroyed, in opponent’s possession without production). Oral evidence prohibition: cannot be used to prove contractual terms when document exists; cannot contradict, alter, add to, or vary documentary terms. This statutory provision applies to: contracts, judgments, grants, property dispositions—any transaction reduced to documentary form. The prohibition is strict: oral testimony about different contract terms is inadmissible regardless of witness credibility or agreement between parties. Exceptions mirror common law parol evidence rule exceptions: proving fraud, mistake, ambiguity resolution, or formation issues. This statutory rule enforces: documentary reliability, preventing false oral testimony overriding written terms, and protecting written contract sanctity. The principle elevates written evidence over oral evidence for matters reduced to writing, recognizing documents’ superior reliability and parties’ intent to be bound by written terms.