The class of witnesses described as expert witnesses is well settled. It is imperative to state that every piece of evidence that has been admitted in the course of proceedings is subject to be tested for credibility, weight or cogency by the trial court before it becomes acceptable. In effect it is not merely acceptable because the witness is described as an expert and his evidence not challenged. The primary duty of the trial court is to evaluate the evidence before it is accepted whether given by an expert or not.
– Nwodo, JCA. OLAM v. Intercontinental Bank (2009)