In a recent article, US organisation, The Expert Institute, outline some cross examination techniques designed to attack the foundations of expert evidence.

While tips around handling depositions are less relevant in Australia and New Zealand (we don’t collect depositions in the same way as they do in the US), the remainder of the article contains some good advice on preparing to cross examine an expert witness. And although pitched at litigators, the article also includes useful information for prospective expert witnesses in the sense that “forewarned is forearmed”.

Here are some further insulation tips for expert witnesses preparing to be cross examined:

  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. ABOVE ALL, DEMONSTRATE INDEPENDENCE: 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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