Dos and Don’ts for Expert Witnesses in the Witness Box

There was a vast gulf in the quality of expert opinion in the case between Dr M on the one hand, and Dr C and Mr C’s on the other.

As his reports presaged, Dr M was discursive and non-responsive in the witness box. He showed strong emotional attachment to his ideas.

On the other hand, Dr C and Mr C were responsive witnesses, who gave reasoned and logical explanations for their views both in writing and in the witness box. I do not doubt that they presented their honest opinions in their reports and in oral evidence.

Dr C and Mr C received unusual instructions and complied with them. I cannot see how the oddities which resulted are their fault.

I have a strong preference for the opinions of Mr C and Dr C, over those of Dr M. [37]

Ms B is a forensic accountant. Her evidence went to the question of loss and damage. Ms B’s evidence was probed and questioned to a limited extent in cross-examination. She was a careful and thorough witness. Her evidence as presented was not extensive, involving narrow questions of accounting for foregone profit based on assumed facts. The only objection to her evidence, properly taken, was the extent to which it relied upon facts or assumptions that were not otherwise established by the evidence.

The main substantive challenge to her evidence came from the competing expert evidence of Mr S. As detailed further in my observations of Mr S, I generally found Ms B’s evidence more satisfactory than his. This was because she explained, or better explained, the basis for the opinions she expressed, while he either did not explain, or did not satisfactorily explain, the basis for several of his key opposing opinions. [80]

Mr S is an accountant. The burden of Mr S’s expert accounting evidence for Mr G was summarised and agreed upon in the short cross-examination of him: he formed a different view than the applicants’ accounting expert, Ms B, as to the calculation of the costs of goods on the potential losses sustained. In short, his opinion was that there were direct expenses that should have been taken into account by Ms B, but were not.

He based his different opinion on his general experience in the calculation of costs of goods sold. He also took a different view as to the appropriate way to calculate Intercad’s gross profit using NCCS pricing because that pricing had a discount applied to it. In the final analysis, the difference between Ms B and Mr S turned not on their credit, or reliability generally, but on which approach was more compelling. As already noted above, I found that Ms B’s approach was to be preferred. [86]

I have been greatly assisted by the evidence given by Mr O and found Mr O to be a reliable, professional and honest witnesses. He attempted to give me every assistance possible in my consideration of the relevant information before the Court. [761]

I found [Mr O] to be an impressive and thoroughly professional witness. During cross examination, it became clear that Mr O was unable to sustain a number of the opinions that he expressed because he had not been properly instructed or because he had not been given all of the necessary documents, or both. [821]

Mr O was a highly qualified and impressive witness. He gave his evidence thoroughly and well. Notwithstanding, I was unable to accept the opinions expressed by Mr O due to the failure by the respondents to properly instruct him and to properly furnish him with all relevant information. Mr O freely and competently made concessions where they were required and attempted to assist me in my task in every way possible. [826]

I found G [expert accountant] to be a careful witness, willing to admit that if any assumptions underlying the expert report he had given were wrong, his analysis might not be correct, and careful to answer the precise questions put to him. [163]

In his report, G dealt with the instructions he was given, and what he was told to take into account. He carefully compared, for example, what he was told were the costs the defendants could have purchased certain items for had they not been in the relevant franchise arrangements, in contrast to what he was told they actually purchased them for. Using this information, he arrived at sums said to indicate Shams’ losses suffered as a result of representations made to her. [164]

The difficulty with G’s evidence is that it does not go anywhere, because the defendants did not prove the assumptions underlying his expert report. In other words, they did not call evidence to establish the truth of the assumptions G was asked to take into account, in making his expert report. [165]

Judges are entitled to take into account the demeanour of party-witnesses, not only in the witness box, but while they enter and leave it, and also while they are sitting in court before and after giving evidence; but observations by the judge of conduct outside the witness box which the representatives of the parties may not have observed, should, if they are influential in the result, be drawn to the attention of the parties so that they may have an opportunity of dealing with the problem.

There is thus no general duty on a judge to advise the representatives of the parties of what they can see for themselves, namely the demeanour of the party-witness in the witness box. Nor, a fortiori, is there a duty on a judge to advise the parties that the party-witness's evidence is not adequate to make out the case of that party-witness. [69]