It is now settled law, that it is the primary responsibility of the trial court which saw and heard witnesses to evaluate the evidence and pronounce on their credibility or probative value and not the appellate court which neither heard the witnesses nor saw them to observe their demeanors in the witness box. It follows therefore that when a trial court unquestionably evaluates the evidence and appraises the facts of a case, it is not the business of the appellate court to substitute its own views for the views of the trial court. – Musdapher JSC. Gbadamosi v. Dairo (2007)
THE COURTS LEAN AGAINST CALLING FRESH EVIDENCE ON APPEAL
Before concluding on the said prayer 7 it is helpful to call to mind the observations of Oputa JSC in Obasi v. Onwuka (1987) 3 NWLR (Pt. 61 ) 364, 372 in an application to call additional evidence on appeal: “To talk therefore of assessing the rightness or wrongness of the trial court’s verdict today by evidence that will be given tomorrow is to talk in blank prose. This is the reason why appellate courts are very reluctant to admit “fresh evidence”, “new evidence” or “additional evidence” on appeal except in circumstances where the matter arose ex improviso which no human ingenuity could foresee and it is in the interest of justice that evidence of that fact be led:- R v. Dora Harris (1927) 28 Cox 432. But by and large, at least in criminal cases (and the principle should also be the same in civil cases), the courts lean against hearing fresh evidence on appeal.”
— Oguntade, JSC. UBA v BTL (SC. 301/2003, 15 April 2005)