Is expert evidence crucial to most cases that cross your desk?
Many – but not all - cases will turn on the court’s assessment of expert evidence. In a professional negligence context the experts tend to be very important and can be regarded as “star witnesses”. That view can be merited. But there can be dangers with making lazy assumptions. Sometimes, clients and advisers can become a little too dazzled by the star quality of their expert and forget some of the basic rules. It is important to remember that experts are ultimately there to assist the court understand matters which the court cannot work out for itself. They are not there to given determinative views on the rights and wrongs of the case.
What are the key rules then for using experts?
In Scotland these can be found in a case called Kennedy v Cordia Services. It was an otherwise unremarkable slip and trip case which found its way to the Supreme Court. The court took the opportunity to provide something of a code for practitioners and experts on the use of expert evidence. If you are an expert or an adviser relying on experts, this case is essential bedtime reading.
Have you had experience of cases collapsing for one side or the other because of poor expert evidence?
Absolutely. You can never legislate for everything that can happen when a case gets into court. However, if you have prepared a case properly, by that time you should have a very clear idea as to the strengths and weaknesses of your expert evidence and what the other side are going to do to challenge them. I have seen inexperienced experts come a cropper because they have obviously spent too long in the room with their own side and not enough time considering their duties in terms of Kennedy. A good example is where an expert thinks it is their job to do all he or she can to advance the case on their side. That can seem useful until it becomes apparent that it is fatal to the expert’s credibility.
What makes a good expert?
That is a very difficult question to answer in a few sentences. Independence is essential. I won a case on appeal where the court at first instance had accepted the expert evidence at trial. However, the evidence was held as inadmissible on appeal as the trial judge had erred in concluding that the expert being on a “no win/no fee” arrangement was not fatal to any notion of him being regarded as independent. The other extremely important thing for experts to understand is the need for a basis for their opinion. The law is clear that an expert who offers an opinion without a suitable basis is offering worthless evidence. It is very important that an expert be asked and then confirm the objective factual or scientific basis for a particular conclusion. Too often clients and advisers can focus on the conclusions and not the working. Finally, experts need to know how to “play the game”. What I mean by that is a general understanding of how litigation works and the manner by which the evidence is going to be tested by the other side and considered by the judge. None of that should ever get in the way of the essential duties, but an expert who understands and complies with his or her essential duties and can offer a clear and robust performance in writing and in court is offering a very helpful combination.
How do you go about cross examining experts?
I use all the rules which make a good expert and try and use them against the expert I am challenging. Quite often, the opinion of the expert is reasonable but the factual basis upon which it is based is flawed. You can sometimes tell that the “what if” question has not been asked of the expert before and that a different opinion might have been expressed if the facts were different. Similarly, the expert can be caught out if they are trying to hard to win for the person instructing them. If the line from robust to non-independent is crossed it can be very damaging. When it comes to the technical side of things you are of course reliant on the quality of your own expert. They should be able to help you understand technical matters so that you can address a meaningful challenge to that side of things.
Are there any developments in how the courts are hearing expert evidence?
There have now been a number of cases where experts are expected to give evidence at the same time. There is a ghastly expression for this process which has unfortunately caught on” “hot tubbing”. The idea is that the court hears from the experts at the same time so that they can respond more directly to the points being taken against them or even agree more easily. There are obviously all sorts of dangers arising from such a process but you can see the benefit to the court. In my experience judges are more enthusiastic about this than counsel. That is because it cedes control which counsel retain if they are in charge of the process of taking the evidence. The key to effective “hot-tubbing” is, again, preparation. The parameters and process should be carefully worked out with the court in advance. If it is not then control will be lost completely and the exercise risks descending into chaos. I have gone as far as constructing a hot tub in a complicated construction project case but I am yet to clamber in. Funnily enough that case settled on the day when the “hot tubbing” was due to begin.