Published date01 December 2004
Date01 December 2004

New rules concerning expert evidence were introduced in 2000 (by the Rules of Court (Amendment) Rules 2000 (S 613/2000)). This article examines recent cases involving experts and considers whether further reform is necessary in the interest of truthful testimony.

I. Introduction

1 The law admits the opinion of an expert witness in order to assist the court in reaching a proper conclusion on a matter which requires the application of special skill or knowledge.1 This is a primary exception to the general rule that opinion evidence is not admissible2— an exception which is justified on the premise that the expert’s input is necessary to the fair adjudication of the dispute. Unfortunately, expert testimony has often obfuscated rather than clarified or simplified the issues so as to defeat its objective. In spite of the well-established methods of judicial scrutiny of opinion evidence in the arena of opposing experts,3 and the new O 40A of the Rules of Court (Cap 322, R 5, 1997 Rev Ed) (“RC”) introduced in 2000,4 recent cases reveal that this area of law may need further development.

II. Problem of expert partiality

2 The problem of expert partiality towards his party is not a recent phenomenon. In 1843, Lord Campbell lamented that “skilled witnesses come with such a bias on their minds to support the cause in which they are embarked, that hardly any weight should be given to

their evidence”.5 The same concern was expressed 150 years later by Lord Bingham when he said:6

[W]hether consciously or unconsciously, the fact is that expert witnesses instructed on behalf of parties to litigation often tend … to espouse the cause of those instructing them to a greater or lesser extent, on occasion becoming more partisan than the parties.

3 Singapore judges have complained about this lack of objectivity over many years. Winslow J observed in Ong Chan Tow v R7 that an expert “would naturally tend to give evidence in favour [of the party who appointed him] — otherwise he would not have been called as a witness”. G P Selvam J commented in The H 156,8“All too often, experts are extremely tendentious towards the parties by whom they are retained”.9

4 Indeed, one of the most intractable problems which may be faced by a court in the course of a case is the extent to which expert testimony is tainted by partiality or bias. The truth of facts can ordinarily be determined by the assessment of the evidence and the application of the principles governing the burden of proof. An opinion is, by its very nature, more elusive because it may only be the subjective inference or interpretation of one person not shared by others. Although many experts do believe in the views which they espouse, the adversarial system encourages polarity of opinions according to the party line. This is not surprising for a party does not appoint an expert at random. The expert is normally chosen because his opinion favours the position of the party. Sometimes considerable effort is put into this task.10 The consequence of this practice is that the opinions of the selected experts often are not representative of the view(s) held by the majority in his profession. The financial interest in giving expert testimony does little to promote objectivity. It has been said:

Indeed in many respects the incentives for the expert to favour one party contrary to their actual belief are substantial. First, expert witnesses are paid for their evidence. Secondly, they may be retained

on a regular basis by a particular client or group of clients in different cases. Thirdly the expert may hope to gain favour with a client generally, perhaps because he hopes that non-legal professional engagements may be forthcoming or continue.11

5 In the course of preparation of the case, the “willing” expert is often primed so that he becomes a member of the “party’s team” in a veritable conflict. In these circumstances, the expert may succeed in postulating an opinion in favour of his party which the expert does not himself believe, if he can justify it as a possible view of the facts. He may do this by over-stressing the plausibility of the opinion and downplaying its weakness. Correspondingly, even though he secretly agrees with the opinion of the opposing expert or believes that it has some validity, he may be astute enough to negate it entirely. Put another way, an expert may able to “hide” the truth behind an opinion if he is partial to the party which called him.12 While an advocate is entitled to present his client’s case in the best possible light irrespective of his own personal views, this is certainly not the prerogative of the expert.13

6 Although the qualifications of an expert have to be clearly established14 and the courts have developed principles to gauge the soundness of an expert’s opinion (particularly in the context of conflicting expert testimony),15 these safeguards do not specifically address the attitude of the expert. They do not prevent an expert from putting forward and justifying an opinion which he does not accept and from denigrating an opinion which he might himself put forward if he had been called by the opposing party. Wise as he may be, a judge does not have the training (which, for example, a psychologist or behaviourist might have) for ascertaining subtle untruths in an opinion. The result is that the court is deprived of the fullness of the witness’s expertise and the information so often determinative of the outcome of a case.

III. Common law principles

7 The principles concerning the impartiality of expert testimony were well established before the introduction of O 40A of the RC. In Whitehouse v Jordan,16 Lord Wilberforce stated:

Expert evidence presented to the court should be, and should be seen to be, the independent product of the expert uninfluenced as to form or content by the exigencies of litigation.17

8 This duty has been examined in a series of cases resulting in the following propositions. He is expected to “provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise” and this includes not assuming the role of an advocate.18 He is required to “state the facts or assumption upon which his opinion is based. He should not omit to consider material facts which could detract from his concluded opinion”.19 He “should make it clear when a particular question or issue falls outside his expertise”.20 If the expert believes that his opinion “is not properly researched because he considers that insufficient data is available, then this must be stated with an indication that the opinion is no more than a provisional one”.21 Should the expert change his opinion on a matter which is “material” (for example, after having read the opposing expert’s report), “such change of view should be communicated (through legal representatives) to the other side without delay and when appropriate to the Court”.22 And where “expert evidence refers to photographs, plans, calculations, analyses, measurements, survey reports or other similar documents, these must be provided to the

opposite party at the same time as the exchange of reports”.23 In Bajumi Wahab v Afro-Asia Shipping Company (Pte) Ltd,24 Choo Han Teck J, having referred to these observations, added:

[I]n discharging his duty, the expert is required to make reasonable appraisement of reasonable factors. Often, he cannot be proved right; and he must thus gain acceptance of his opinion by the depth of his research, the soundness of his analysis and arguments, and the honesty and impartiality in which he presents his views.

IV. Order 40A rules 2 and 3(g) and (h)

9 When O 40A of the RC was introduced in 2000,25 it affirmed and formulated the existing common law principles. Rule 2 states:

(1) It is the duty of an expert to assist the court on the matters within his expertise.

(2) This duty overrides any obligation to the person from whom he has received instruction or by whom he is paid.

Rule 3(2)(g) requires the expert to state in his report that he believes in the correctness of his opinion. Furthermore, pursuant to r 3(2)(h), he must state that he “understands that in giving his report, his duty is to the court and that he complies with that duty”. These two paragraphs have a particular significance in respect of the liability of an expert. An expert who gives evidence of an opinion which he does not believe to be correct may be prosecuted for perjury pursuant to s 191 of the Penal Code.26 Paragraph (g) emphasises this duty and para (h) compels the expert to declare his awareness of it.

10 The new rules were first considered in Gunapathy Muniandy v Dr James Khoo,27 where Selvam J stated:

The expert must not only be impartial but must also appear to be so. The expert should avoid being the witness of a party with whom he has a special relationship. If that is unavoidable he must disclose the relevant facts. On this point there must be absolute transparency from

the expert witness and his legal adviser for they are both officers of the court.

11 With respect to the learned judge, the fact that the expert has a duty to the court does not make him an officer of the court. Nevertheless, the duty is a clear and emphatic one. The assumption in this passage that an expert may give evidence despite the existence of a “special relationship” between him and the party will be analysed in the context of recent English decisions on the point.28

12 The rules were next considered in Vita Health Laboratories Pte Ltd v Pang Seng Meng29 (“Vita Health”), in which V K Rajah JC said of O 40A r 2(2):

This duty implicitly obliges him to give testimony that may harm or damage the contentions of his instructing party, if the facts warrant this.30

The learned judge emphasised:

It may be said — albeit with some exaggeration — that while an advocate may be as biased as he chooses to be in pressing...

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