A keynote paper presented to the Expert Witness Institute Online Conference in May 2022 by Lord Hamblen of the Supreme Court of the United Kingdom is now available online, here.

For those of us who do expert work, “The modern expert: personal insights and current issues” is well worth reading in its entirety, but in my opinion the best advice is:

[17] …do what you can to make it easy for the judge to understand your expertise and your expert views. This involves explanation. Do not assume prior knowledge and understanding. In simple and clear language try and make it easy for a judge to assimilate and to understand.

Make clear what your underlying assumptions are and set out all the building blocks which lead to the conclusions that you reach.

That may involve covering what seems like basic ground for you, and possibly for the judge, but it is far better to err on the side of cautious simplicity than diving straight in to the key disputed issues.

[18] …Make a conscious effort to simplify and to clarify.

[20]…All the opinions you express and the conclusions you draw must be supported by reasoning. Those reasons must be clearly set out and explained.

Make sure, however, that the supporting reasons are cumulative rather than individually critical. You want to avoid the risk of your expert opinion being undermined if one building block is taken down.

Try and build as effective defences as you can for any opinion you express. This means careful and convincing reasoning.

[21] …do what you can to try and gain the judge’s trust and confidence. This means demonstrating objectivity and an awareness of your duty to the court, not just your client.

Be prepared to make concessions even if that appears to be against your client’s interest in winning the case. Acknowledge errors or omissions, if made.

[28]…the clearer your oral evidence is, the better it will be understood and the greater its likely impact. Clarity in the giving of oral evidence involves keeping to the point and making your points in shortly expressed but plain language. Avoid speeches.

[29]…Show that you have been even handed and are concerned to arrive at the right answer rather than simply the answer that may suit your client. As it is put in one of the cases to which I shall be referring [my note: this one], give the impression that your evidence would have been exactly the same if you had been instructed by the other side.

[33] There is nothing more fatal to the acceptability of an expert’s evidence than concerns about their independence and impartiality.

[34] …avoid being an advocate. It is counsel’s job to argue the case. That is not the role of the expert. If you give your evidence in an argumentative manner that will inevitably undermine that evidence and risk allegations of partiality. Counsel may try to provoke you and to get a rise from you, but you must retain your clear-headed objectivity.

Make points, explain points, but do not argue them. Never get into an argument with counsel, however provoked you may be. If you are not being treated fairly in cross examination then your counsel or the judge will usually intervene. Do not, however, take matters into your own hands.

[35] …know the limits of your expertise…do not stray into areas of non-expertise. You are being asked to give expert opinion evidence. That opinion evidence is only admissible because it is expert evidence. But keep to your expert opinions.

Do not stray into judgments as to the facts. Ensure that the evidence you give is and remains the expression of your expertise and nothing else.”