Proofing your evidence against cross examination king hits


Cross examination can be like a boxing match

In a February 2021 articleThe Expert Institute liken the cross examination process to that of a boxing match, quoting the late Mohammed Ali:

“The fight is won or lost far away from witnesses – behind the lines, in the gym, and out there on the road, long before I dance under those lights.”

The article then analyses specific preparatory techniques designed to attack the foundations of an opposing expert witness' evidence. The article's advice is pitched at cross examining litigators; however, as "forewarned" is "forearmed" , expert witness are likely to find it insightful too.

(Although note that experts in the US courts are not bound by the same duty of independence as those in Australia and New Zealand; we also don’t collect depositions like they do in the US).

Insulation tips for expert witnesses

The article reinforces the need for expert evidence to be supported by a strong foundation. Here are some further things to consider when undertaking the role of expert witness.

1. Understand the facts:

Expect to be challenged on your understanding of the facts. Set out all facts that you have investigated yourself and those which you are being asked to assume for the purpose of expressing an opinion. As much as possible, test them. Have you taken into account all material facts? Conversely, have you confined yourself to matters in dispute and within your area of expertise? Be sure in advance whether your opinion would change (or, perhaps even more importantly, the extent to which it might) if the underlying facts were different.

2. Be mindful about your investigation:

Are you aware of best practice in investigative techniques? Are your notes and records Clear, Intelligible and Accurate? Are there obvious gaps in your knowledge? What independent steps have you taken to become more informed? Have you been transparent about the process that you followed? is that process set out in your report?

3. Adopt a robust methodology

Have you set out the methodology used in conducting any tests of a scientific or technical nature? If these tests were undertaken by somebody else, have you identified that person and any supervisor, along with their respective qualifications and experience? Does the methodology used accord with generally accepted standards and/or scientific protocols? If you have departed from usual practice at any point, explain in simple terms the reason why this was deemed necessary. Are there any statistical anomalies in your results that could be exploited? If so, be prepared to explain their significance to your overall conclusion and describe any measures you took to protect the integrity of the results.

4. Strike a balance

Your opinion may be criticised for being too general or damned for being too fact-specific. How do you win? The best approach is to strive for a healthy balance. Provide enough general theory, academic literature etc to demonstrate your expertise and give the opinion sufficient context. And then practically apply this same theory, logically and relevantly, to the facts at hand.

5. Demonstrate independence:

Above all else, exude impartiality and detachment from any particular outcome. The more that you come across as unaffected by the pressures of litigation, the less likely any cross-examination “hits” will damage your credibility as an expert witness. This does not mean necessarily conceding points under cross examination: you are entitled to stand up to attacks on your evidence, firmly and resolutely. But do resist the temptation to defend your position too vigorously. Remember that your role is to assist the court, tribunal or arbitral panel on issues within your expertise – you are not there as an advocate.


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