Why is an expert Range Of Opinion so stressful for lawyers? - Dr Mark Burgin
30/01/23. Dr Mark Burgin reflects on the problems that lawyers have with medical uncertainty and the expert range of opinion.
There appear to be two constants in expert evidence, first that the experts have uncertainty and second that they disagree. These are two parts of the same problem, that there is a range of opinion with experts at different places on that range. Ideally all experts would offer a range of opinion and reduce the need for further experts. In reality each expert will usually offer their own opinion as it was certainty.
The courts generally praise experts who offer ranges of opinion and in Practice Direction under 3.2 (6) mandates a range of opinion. Lawyers however appear to find the uncertainty that these statements make difficult to manage. This results in experts who offer ranges of opinion being instructed to remove them because they were not asked for that (or similar).
Few expert reports contain ranges of opinion and part of the reason is likely to be that lawyers find them difficult. Lawyers can feel that ‘their’ expert has betrayed them by putting points that are helpful for the other side. Clinical negligence cases are usually settled once the range of opinion is identified which can make the lawyers feel powerless.
Hotson v East Berkshire AHA [1987] AC 750
Hotson is a historic case that lawyers will recognise as loss of a chance but for medical experts it is better known for the problems of range of opinion. The boy fell from a tree and broke his hip and the hospital missed the diagnosis. The loss was avascular necrosis of the femoral head. The question was whether it was the breach or the fall which caused the arteries to tear and deprive the femur head of blood.
The experts agreed that the medical evidence did not favour either explanation and maintained their range of opinion under cross examination. The judge was not happy with this answer as it would mean presuming that a fall which caused fracture would also tear the arteries unless the child leg was handled roughly.
It is worth noting that the judge would have had a description by the A and E department of the injury and contemporaneous findings, the imaging and the family’s description of what the claimant did after discharge, all of which would have been material to the issue. The experts did not appear to have had access to literature, a recent study confirms that 2-3 arteries were likely to have been torn at the time of the fall.
Child abuse cases
Assessing child injuries to determine if they are accidental or non accidental NAI is a very controversial area where there is a range of opinion. The result is that experts often will state that the neuroimaging is not more likely than not to have had a NAI cause. Most paediatric neuroradiologists do not routinely examine children for NAI so find these questions difficult.
The correct approach is to offer a range of opinion but should avoid saying some experts say NAI and others say accidental. Instead they should use the Istanbul Protocol (see below) which while created for scars is applicable to any trauma. The expert could then indicate their level of certainty on a scale and differentiate between the mechanism which is often clear and the intention which is outside of even a paediatric specialist’s expertise.
There is a tension between those who do not want to let a criminal walk free and those who do not want innocent people to go to jail. Experts can use ambiguous wording such as ‘consistent’ without explaining that it could mean an average of 20% of these injuries being caused that way. Range of opinion is essential to all expert evidence but particularly those areas where emotions run high.
Lack of familiarity
The main reason why lawyers get stressed with range of opinion statements is lack of familiarity. I have seen this first hand where the barrister took one end of a range of opinion and asked me if it was my opinion. I replied that some experts would take the opinion that the claimant was correct. Then I read the rest of the sentence which included the opinion that the claimant was wrong.
Another case was where expert’s interpretation of the law was in issue. The barrister stated that only the court’s opinion of the law mattered. I explained that some experts were of the opinion that the action breached the law and others did not, which explained why my opinion differed from the other expert. The experts both had agreed that there was a range of opinion and that doctors should follow the law.
A common issue that arises is how much risk should a doctor take when managing a condition. Some doctors take high risk and only refer when they are certain, others take low risk and refer everyone who might have the condition. Doctors know that telephone assessment is more risky but still use it as they feel they have no other choice.
Conclusions
Practice Direction part 35 civil procedure rules states at (6) where there is a range of opinion on the matters dealt with in the report – (a) summarise the range of opinions; and (b) give reasons for the expert’s own opinion. This is remains good advice and should be followed more frequently but may not on its own be enough.
There is strong evidence that many difficulties in court cases arises from an incomplete or absent statement of the range of opinion. The expert should recognise that their views are not likely to be held by the other side and be able to explain both points of view. This may involve saying things that sound extraordinary if they reflect the range of expert opinion.
A range of opinion on its own may be insufficient in complex cases. It is essential to consider whether other evidence is available which might alter where on the range is correct. As lawyers become more familiar with ranges of opinion they are likely to share the court’s enthusiasm for clearer and more independent opinions.
Doctor Mark Burgin, BM BCh (oxon) MRCGP is on the General Practitioner Specialist Register.
Dr. Burgin can be contacted on This email address is being protected from spambots. You need JavaScript enabled to view it. and 0845 331 3304 website drmarkburgin.co.uk
The Significance of Evaluating the Femoral Head Blood Supply after Femoral Neck Fracture: A New Classification for Femoral Neck Fractures Dewei Zhao 8 = no vessel injury, 20 = one retinacular vessel injury, 35 = two retinacular vessel injuries, 10 = three retinacular vessel injuries.
Istanbul protocol scar classification
(a) Not consistent: the lesion could not have been caused by the trauma described; (b) Consistent with: the lesion could have been caused by the trauma described, but it is non-specific and there are many other possible causes; (c) Highly consistent: the lesion could have been caused by the trauma described, and there are few other possible causes; (d) Typical of: this is an appearance that is usually found with this type of trauma, but there are other possible causes; (e) Diagnostic of: this appearance could not have been caused in any way other than that described.
Image ©iStockphoto.com/GOCMEN
This is part of a series of articles by Dr. Mark Burgin. The opinions expressed in this article are the author's own, not those of Law Brief Publishing Ltd, and are not necessarily commensurate with general legal or medico-legal expert consensus of opinion and/or literature. Any medical content is not exhaustive but at a level for the non-medical reader to understand.
