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FREE BOOK CHAPTER: Why Get an Expert? (From 'On Experts: CPR35 for Lawyers and Experts' by David Boyle)

10/01/17. Court cases normally involve the interaction of evidence, law and procedure, albeit that often one or more of those aspects withers on the vine. The legal and procedural aspects of the case should fall outwith this volume, which concentrates on evidential issues, although there are clearly circumstances where the expert's evidence actually pertains to legal or procedural matters.

In the normal course of events, the parties to litigation are able to provide evidence to the court. Whilst parties are under a duty to disclose relevant documentation,1 the starting point for evidence is normally a witness statement, setting out the oral evidence which a party would give at trial.2 That statement must, if practicable, be in the intended witness’s own words, should be expressed in the first person, and must indicate which of the statements in it are made from the witness’s own knowledge and which are matters of information or belief, together with the source for any matters of information or belief.

Those requirements of 32PD.18 are important, because, if followed properly, they limit a witness’s evidence to factual statements. If one writes in the first person, it naturally limits the narrative to matters within one’s own knowledge, even if the information is not directly known, but comes from another.3 Importantly, when one strays into opinion, it is difficult to avoid saying so, either expressly or impliedly.4 That, in turn, is important because whilst a lay witness can give evidence of fact, he cannot give opinion evidence. It is inadmissible as a matter of law.

That means that, whenever a litigant needs to prove something beyond his own knowledge, or capacity to give evidence, he needs, in theory at least, evidence from somebody who, as a matter of law, has that knowledge and/or specific skill and competence to opine on the subject. This ties in with the concept of ‘judicial notice’ whereby if a specific fact is so well known that there can be no doubting it,5 or is officially recorded,6 there is no need for formal evidence to be called to prove the point.

In an age where proportionality is fundamental to the litigation process, there is a temptation to presume that the court will take judicial notice of more and more, but there is a very real need to take care not to overstep the mark. It is easily done, but it is not for lawyers, or judges, to impose their personal view of a situation and assume the position of expert in a case. The reason is relatively obvious, but nevertheless often ignored. Whilst we spend our lives making judgment calls on the specific facts before us, if those facts fall outwith our understanding, often because we cannot appreciate the macro scale, we fail to have adequate regard to the bigger picture. Unless one has specific understanding, one cannot comprehend how often an event might take place, and without that comprehension, one cannot simply guess at the effects when it occurs on a specific occasion.

To give an example of our lack of understanding of scale, imagine that the UK appointed an annual Public Philosopher, to whom each person in the UK paid one penny a week to think radical thoughts on their behalf. 63½M people would pay their weekly penny (because even a child might find a penny) and at the end of the year our philosopher would have been paid £33,020,000. Most people would struggle to understand what that amount of money might actually mean. It isn’t lack of intellect or education which restricts that comprehension, but a lack of experience. Time and again we hear of lottery winners who spent everything they’d won – they simply did not understand the meaning of money.

In those circumstances, the question as to whether one needs an expert is, to some extent, a question of judgment for the lawyer, the litigant or the case managing judge. The difficulty is that the judge in question is unlikely to be the tribunal at trial. A district judge, trying to impose a sense of proportionality on a case, might baulk at permitting the parties to spend more than the potential value of the claim on an expert whose evidence might only serve to rubber stamp the contentions made by the litigants, only for the case to take a twist at trial which renders that evidence necessary and the claimant’s case (and it will normally be the claimant’s case) compromised by its absence.

The court, however, is mandated by CPR35 to restrict expert evidence to that which is reasonably required to resolve the proceedings. There is inevitably an onus on the party wishing to rely on an expert to justify the need for that evidence, and that means that there needs to be a clear understanding of the litigation process and the issues which are going to arise in the specific litigation before instruction is actually made. That normally involves the parties engaging in constructive discussion about what falls to be determined, or, alternatively, the claimant’s advisors having a sound basis to believe that the point in issue will need to be resolved in due course.

1 Disclosure is governed by CPR34 and is outwith this book.

2 Lay witness evidence is governed by CPR32.

3 “My neck was sore after the accident. The doctor told me that I had a whiplash injury. I took painkillers and was pain-free the next day. I have not suffered any pain since.”

4 “In my opinion, any symptoms that I had in my neck were caused by the accident.”

5 E.g. The boiling point of water in normal circumstances. There are, of course, a number of factual issues to be considered, even on this point. What are ‘normal circumstances’? It is commonly known that altitude affects the boiling point of water but we immediately see that there are degrees of knowledge. Does it make a difference if one is 500m above sea level? What about 1,000m? How accurate does the answer have to be on the facts of the case? Clearly, if one were looking at whether a specific piece of machinery could operate when the boiling point temperature dropped below 98°C, expert evidence would become critical and an expert would almost certainly be required. If, on the other hand, the question was “Does water from a just-boiled kettle have the capacity to scald?” the Court might take the view that the answer was so obvious that it could take judicial notice. Of course, we now have kettles which heat the water to different temperatures depending on the drink the user wants to make.

6 E.g. The time of the high tide on the day in question.


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