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How far can you go with expert evidence in a clinical negligence claim?


    Paul Rumley examines how far the Court will let you go, in terms of expert evidence, in looking at all of the possible consequences arising from clinical negligence, including whether or not you can have your own expert or if you have to instruct an expert jointly with the Defendant.

    By Paul Rumley

In all clinical negligence cases it is necessary to seek input and advice from specialist medical experts. These experts provide independent advice on issues such as the standard of medical treatment provided, whether the patient has suffered avoidable harm as a result of any substandard medical treatment and also the nature of the harm suffered and the prognosis for the injuries.  Experts can be instructed by either party, or in some cases by both parties jointly.  A recent reported clinical negligence case has looked at the issue of single or joint instruction of experts.

The Case – Yearsley v Mid Cheshire Hospitals NHS Trust

In the ongoing case of Yearsley v Mid Cheshire Hospitals NHS Trust the Claimant is pursuing a claim that he developed chronic infection to his right foot following surgery. In brief, it is alleged that this, in turn, led to surgery to the shoulder for septic arthritis which in turn caused or exacerbated dementia.

The Claimant wanted to instruct an expert to consider the link between his physical surgery, and his dementia and therefore whether that formed part of the injury he could claim compensation for as being caused by the negligent medical treatment he received originally.

The Defendant Trust tried to resist the Claimant being able to obtain and adduce this further evidence, despite their own instructed expert indicating that the Claimant did indeed have significant dementia which required a proper assessment. They argued that either a single joint expert (one expert instructed by both parties at the same time) should be instructed, or at least a single expert should conduct the testing for dementia.

What’s the problem with having a single joint expert?

If you have a single joint expert, there are a number of potential complications for the claim:

  • You cannot have any discussions or correspondence with the expert, without that being copied to the Defendant or them being present. This presents real logistical difficulties for investigating and fully developing the claim as it can inhibit open and honest discussion of the strengths and weaknesses of the evidence.
  • Following on from the above, if you get an opinion from a single joint expert which initially goes against you, that can prejudice the claim in respect of that evidence even if the expert were to change their mind later on once they have had a chance to clarify their opinion. In essence you are stuck with the opinion, unless you instruct another expert.
  • Following on from the above, and as well identified in this case, the risk of ending up with multiple expert reports even where a single joint expert has initially been instructed, only serves to complicate the matter and therefore increase costs which the Courts are very keen to keep down.

The Decision

The Judge, Mrs Justice Whipple, considered the arguments made by both parties in June 2016. She noted in her judgment that she was very mindful of the costs of additional expert evidence, but found the following:

  • If the Claimant had dementia it would have an impact on the Trial.
  • If dementia was found to be part of the claim, if there is a single joint expert the Claimant might be inhibited from having frank discussions with that expert to inform their opinion.
  • The Claimant was allowed to instruct his own expert psychiatrist with expertise in diagnosing dementia first. That report would then be served upon the Defendant Trust, and they could then decide whether they accepted its contents and if not then they could instruct their own expert to provide further opinion. The benefit of that, the Judge felt, was that if the tests carried out by the first expert produced objective data then any further experts would be able to use that, and comment upon it without having to go to the time and expense of repeating the tests.


It is of vital importance that Claimants, who have the burden of proof in a clinical negligence claim, are allowed to fully and openly investigate their claim, and understand what the strengths and weaknesses are. Single joint experts, in certain circumstances, can inhibit that for the reasons set out above. To that extent, the Court therefore go primarily with the Claimant instructing an expert first, to see if the Defendant would accept the findings and thereby reduce the costs of litigation.

In my experience, Defendants increasingly push for single joint experts in lots of claims. This case is a timely reminder that they will not necessarily be successful in such arguments, because that may not be appropriate in certain cases, and that Claimants need to consider arguing for their own expert. It is still an issue which needs to be decided on a case-by-case basis, depending on the importance of the issues the expert needs to advise on, and should not be conceded readily or automatically by specialist Claimant clinical negligence solicitors.

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