#22 Lessons from the Courtroom – Do’s and Dont’s for Expert Witnesses in the Witness Box

The conduct of an expert witness in the witness box is frequently commented on by Judges in their assessment of the evidence presented before them.

Expert evidence – in both written form in the witness box – is a critical element of any legal proceedings. However, it is an Expert’s conduct in the witness box under cross-examination that is often the most commented upon by the Court through the judgments published.

Generally, where a Judge comments about an expert’s evidence and is often accompanied by contrasting expert evidence, which appears to be a contributing factor to the gap between experts in a particular matter.

In the QSC matter of Landel Pty Ltd v Insurance Australia Ltd[2021] QSC 247, the Judge made the following remarks about the expert evidence presented:

There was a vast gulf in the quality of expert opinion in the case between Dr Macintosh on the one hand, and Dr Connor and Mr Caddis on the other. As his reports presaged, Dr Macintosh was discursive and non-responsive in the witness box. He showed strong emotional attachment to his ideas. On the other hand, Dr Connor and Mr Caddis 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 Connor and Mr Caddis received unusual instructions and complied with them. I cannot see that the oddities which resulted are their fault. I have a strong preference for the opinions of Mr Caddis and Dr Connor over those of Dr Macintosh. [37]

The FCA judgment of Central Innovation Pty Ltd v Garner (No 4) [2020] FCA 1796 details how the Court sided with the expert that was ‘more compelling’:

Ms Bateman is a forensic accountant. Her evidence went to the question of loss and damage. Ms Bateman’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 Scarr. As detailed further in my observations of Mr Scarr, I generally found Ms Bateman’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 a number of his key opposing opinions. [80]

Mr Scarr is an accountant. The burden of Mr Scarr’s expert accounting evidence for Mr Garner was summarised and agreed upon in the short cross-examination of him: he formed a different view than the applicants’ accounting expert, Ms Bateman, 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 Bateman, 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 Bateman and Mr Scarr turned not on their credit, or reliability generally, but on which approach was more compelling. As already noted above, I found that Ms Bateman’s approach was to be preferred. [86]

An Expert is expected to make reasonable concessions as their ultimate duty is to the court, but this can often be at the detriment of the party instructing the Expert. The reasoning as to why an Expert would make reasonable concessions and still be seen by the Court as an ‘impressive and thoroughly professional witness’ is demonstrated in Gabjet Pty Ltd & Anor V Funk Franchise Pty Ltd & Ors [2021] SADC 88:

I have been greatly assisted by the evidence given by Mr Opie …... I found [him] to be 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 Opie] to be an impressive and thoroughly professional witness …. During cross‑examination, it became clear that Mr Opie 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 Opie 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 Opie due to the failure by the respondents to properly instruct him and to properly furnish him with all relevant information. Mr Opie freely and competently made concessions where they were required and attempted to assist me in my task in every way possible. [826]

And again similar findings in Sigma v Shams [2021] VCC 713:

I found Gwynne [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, Gwynne 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 Gwynne’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 Gwynne was asked to take into account in making his expert report. [165]

What is the Court telling us?

The Court is telling us that as an Expert Witness we should:

1. Give reasoned and logical explanations of our views in both written form and in the witness box
2. Make reasonable concessions in the witness box when cross-examined about our conclusions and/or the assumptions underpinning our report
3. Be thorough, thoughtful and careful in our responses under cross-examination
4. Do not be ‘emotionally’ attached to your ideas such that you are not willing to make reasonable concessions

Expert Witnesses are a key party to a case and the quality of their opinions can have a significant impact on proceedings.

For more information on the services the Forensic consulting team – including Expert Witness services – at Grant Thornton Australia provide to family and commercial lawyers, please contact me or your local contact.