Valuable lessons for expert witnesses from recent legal cases

Our legal system relies on experts to assist the Court in ensuring justice. Experts play a very important role. However, according to a recent judgment, there is a worrying trend of experts failing to comply with their duties and this case is a helpful reminder of how things can go wrong¹.

The failures concerned two requirements of the Practice Direction to the Civil Procedure Rules (CPR) Part 35:

2.1 Expert evidence should be the independent product of the expert uninfluenced by the pressures of litigation.

2.2 Experts should assist the court by providing objective, unbiased opinions on matters within their expertise, and should not assume the role of an advocate.

The claim

This was a professional negligence claim, with the claimant seeking damages against consulting engineers. The claim concerned the design of foundations for two blocks of housing to be built on Sussex clay, a design which was found to be negligent. The claim by one claimant failed and the claim by the other succeeded, but only to the tune of £2,000 and not £3.7 million. Since the defendants' offers to settle the claims, first for £50,000 and then for £110,000, were rejected, the claimants were ordered to pay the defendants' costs. 

The defendants sought to recover costs on the indemnity basis, rather than the less generous standard basis. One of the grounds they put forward was the conduct of one of the claimants' experts, Mr Hughes. In fact, while the judge thought that the expert's approach to his task "left much to be desired", he did not award indemnity costs. He nevertheless cautioned that, "Parties to litigation who rely upon expert evidence that fails to comply with the rules should not be encouraged by my finding" and went on to identify the "worrying trend".

Criticisms of the expert witness

In his judgment in the substantive claim², the judge had made several criticisms of Mr Hughes. They read as a cautionary tale of how not to give evidence. 

1. Mr Hughes constantly embellished his criticisms of the defendant and exaggerated. The defendant's counsel described certain comments as "frankly farcical, descending into hysteria". The judge criticised them (in more measured terms) as "somewhat extreme". 
2. He constantly introduced new concepts or issues. He appeared to be seeking to bolster the claimants' case.
3. In cross-examination, Mr Hughes relied on material that had no relevance to the case.
4. He changed his mind on a point and disavowed his previous evidence when it was clear that it did not assist the claimants' case.
5. The expert witness went further than was justified by his own expertise in what amounted to a lack of objectivity.
6. Whereas the defendants' expert gave the impression that his evidence would have been the same had he been instructed by the other party (and this is often described as the 'useful test of independence'), "the same could not be said of Mr Hughes".
7. The expert witness constantly sought to advance the claimants' case at the expense of expert objectivity.
8. He ignored points that were unhelpful to the claimants' case.
9. Some of Mr Hughes' evidence was "patently incorrect".

Lessons for expert witnesses

There are important lessons for expert witnesses here on the importance of independence and objectivity. As an expert witness, your role is to assist the Court on matters within your expertise. 

• You are required to be independent. 
• Your evidence should be the same, whichever party is instructing you. 
• Your role is not to fight one party's case or to act as an advocate. 

Bear in mind that, at trial, your evidence will be scrutinised. Cross-examination is often a very effective way of exposing frailties in evidence. Reading publicly available criticisms of your conduct will be a very uncomfortable experience. So, it's important that you always act with impartiality in expert witness work.

¹ Beattie Passive Norse Ltd and NPS Property Consultants Ltd v Canham Consulting Ltd, Judgment No.2 (Costs) [2021] EWHC 1414 (TCC)
² Beattie Passive Norse Ltd and NPS Property Consultants Ltd v Canham Consulting Ltd, [2021] EWHC 1116 (TCC)