Philip O Nwachukwu
As a general rule under Nigerian law of Evidence, the opinion evidence is irrelevant in court trials. Thus section 66 of the Evidence Act CAP E14, Laws of the. Federation of Nigeria (LFN), 2004 provides that the fact that any person is of the opinion that a fact in issue, or relevant to the issue, does or does not exist, is irrelevant to the existence of such fact except as provided in sections 57 to 65 of the Evidence Act. Exceptions to this general rule are contained in sections 57 to 65 of the Evidence Act, which make opinion of experts and non-experts relevant with regard to foreign law, native law and custom, points of science or art, identity of hand-writing or finger impressions, native law and custom, certain usages and tenets, existence of the relationship of one person to another, etc. Section 57 subsections (1) and (2) specifically provides: “(1) When the court has to form an opinion upon a point of foreign law, native law or custom, or of science or art, or as to identity of handwriting or finger impressions, the opinions upon that point of persons specially skilled in such foreign law, native law or custom, or science or art, or in questions as to identity of handwriting or finger impressions, are relevant facts. (2) Such persons are called experts” The need for experts or persons specifically trained or qualified in particular discipline to assist the court by testifying on causation arising from certain phenomenon studied by them is acknowledged by this section (section 57 (1)) --- i.e., expert opinion (in oral or written form) is admissible under section 57 of the Evidence Act. Expert opinion is particularly very necessary where the phenomenon being inquired into by the court is beyond the knowledge of a mind (e.g., judges, magistrates and judicial officers) untrained in the discipline or art concerned. As an example, in the Nigerian case of Seismograph Service v. Ogbeni (1976)1 NMLR 290, the court held that evidence of an expert was absolutely necessary to prove damage alleged to be caused by vibrations from seismic operations taking place within a reasonable distance from the property damaged, these being phenomena beyond the knowledge of the unscientific and the untrained in seismology and civil engineering. See also the United States case of Lorraine v Markel Am. Insurance Co, 241 FRD 534 (D. Md. 2007), where the court admitted the opinion of experts in order to ascertain if the damage to Lorraine’s yacht was caused by lightning. Thus section 60 of the Evidence Act provides that where the opinions of experts are relevant, facts, not otherwise relevant, become relevant and admissible if they support or are inconsistent with such expert opinions.
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HOW TO TENDER EXPERT EVIDENCE To be admissible, expert opinion must be -a) given or tendered directly by the expert himself; or b) where the opinion is already expressed in a treatises or book commonly offered for sale, the opinion may be proved by production of such treatise or book if (i) the author is dead or (ii) cannot be found or (iii) is incapable of giving evidence or (iv) cannot be called as a witness without an amount of delay or expense which the court regards as unreasonable. (see section 77 (d) (i) of the Evidence Act) Section 77 (d) (i) of the Evidence Act provides: “Oral evidence must, in all cases whatever, be direct – (d) if it refers to an opinion or to the grounds on which that opinion is held, it must be the evidence of the person who holds that opinion on those grounds: Provided that – (i) the opinions of experts expressed in any treatise commonly offered for sale, and the grounds on which such opinions are held, may be proved by the production of such treatise if the author is dead or cannot be found, or has become incapable of giving evidence, or cannot be called as a witness without...