The rule excluding evidence of opinion is traditionally stated in broad and general terms, subject to a more or less closed list of exemptions. Stephen says that a witness’s opinion is “deemed to be irrelevant”. A witness may depose to the facts which he has observed, but he may not ordinarily state any inferences which he has drawn from those facts, or opinions founded upon facts of which he has no personal knowledge. The general rule is that the evidence of opinion or belief of a witness is irrelevant because it is the function of a court to draw inferences and form its opinion from the facts; the witnesses give evidence as to the facts and the court forms its opinion from those facts. The opinion of an expert is admissible if it is relevant. It will be relevant if the witness’s skill, training or experience enables him materially to assist the court on matters in which the court itself does not usually have the necessary knowledge to decide. Where the topic is such that an ordinary judicial officer could be expected to be able, unassisted, to draw an inference, expert evidence is superfluous. In principle, there is no rule that a witness cannot give his opinion on an issue that the court has to decide ultimately. It is not experts alone who may give their opinions on ultimate issues but, in practice, there is a strong tendency to regard the evidence of lay persons on ultimate issues as constituting prima facie evidence only. If such lay testimony remains unchallenged, it may be of greater significance. It is generally true that relevant evidence is admissible and irrelevant evidence is inadmissible. At this stage the following question may be posed: is the opinion of any witness – whether from an expert or lay person – admissible evidence? Should an opinion be admitted for purposes of persuading the court to rely on it in deciding the issue at hand? The basic answer is that relevance remains the fundamental test for admissibility. Certain issues simply cannot be decided without expert guidance. Expert opinion evidence is therefore readily received on issues relating to ballistics, engineering, chemistry, medicine, accounting and psychiatry, to mention only a few examples. The problem which arises is this: what is the best way of cross-examining the expert witness? Although the concept of skilful cross-examination conjures up the image of the crossexaminer destroying the expert witness in the witness box, total annihilation of expert evidence in court occurs only rarely. In reality, lawyers who are expected to cross-examine experts are often at a disadvantage in that they do not possess sufficient in-depth knowledge of the specific field of expertise to enable them to cross-examine the witness. Despite the expert nature of the evidence, it is suggested that the true basis of crossexamination should not be abandoned when dealing with experts. The effectiveness of crossexamination is enhanced by keeping the number of questions to a minimum as well as opening and concluding with good strong points. At the outset it should be mentioned that there is a distinction between matters of scientific fact and matters of mere opinion. On matters of scientific fact experts seldom differ but within the province of opinion one encounters difficulties. Lengthy cross-examination concerning expert’s theoretical knowledge is usually inefficient and should rarely be attempted. Cross-examination should be directed at pure logic or scientific analysis. The cross-examiner should always have relevant authority with him in court so as to confront the expert with these. The whole effect of the testimony of an expert witness can also be destroyed by putting the witness to test at the trial as to his qualifications, his experience and his ability and discriminations as an expert. A failure to meet this test renders his evidence nugatory.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:10166 |
| Date | January 2005 |
| Creators | Dumani, Msebenzi |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Law |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, LLM |
| Format | 77 pages, pdf |
| Rights | Nelson Mandela Metropolitan University |
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