Expert witness evidence, logic and breach of duty

  • Published: June 02, 2020
  • Author: Paul Sankey, Partner, Enable Law

The recent case of Bradfield-Kay v Cope[1] is interesting for two reasons. First, in a re-run of David and Goliath (without the sling), the Court preferred the evidence of the less specialist of two medical experts on the grounds that it was more logical. Secondly, it appears to be an application of the Bolitho approach to breach of duty, despite the judge specifically saying it was not.

The facts

The claimant underwent a right total hip replacement in November 2009, and then the same procedure to his left hip in December 2009. Both operations were carried out by a private orthopaedic surgeon, Mr Cope. The first was successful but the second was not and the claimant reported painful clicking. He then consulted a second surgeon, Mr Hemmady, who performed a revision. In the operation note, he commented that the cup was found to be retroverted, its anterium was prominent and was catching on the anterior structures.

The clinical negligence claim

The claimant sought damages alleging negligence in three respects.

  1. That Mr Cope had incorrectly positioned the acetabular component (cup) so that the iliopsoas tendon caught on it, causing tendonitis. This allegation is the focus of this article because it gave rise to the two points of interest.
  2. That he had used the wrong size femoral component. In this, the claimant succeeded largely because, on the evidence, Mr Cope appeared to have based his choice of component on a mistake as to what he had used in the previous operation.
  3. That he had failed to record and act on a report of groin pain at a later appointment. This allegation failed.

The expert witness evidence

Both parties relied on expert evidence from orthopaedic surgeons: Mr Chatterji, for the claimant, and Mr Manktelow, for the defendant. While Mr Chatterji conducts total hip replacements, the primary focus of his practice is knee replacement surgery. Mr Manktelow's practice was largely primary and revision hip arthroplasties, and had included 103 revisions in three years. He was a past president of the British Hip Society and had published widely on hip arthroplasty. Of the two experts, he was significantly more specialist and the Court found that he was better able to "speak to the practice of hip specialists in England". That might have seemed to augur well for his evidence.

The two experts agreed on most issues: 

  • that the claimant had developed irritation of the iliopsoas tendon
  • the cause was an acetabular component, which was prominent
  • what amounted to an acceptable position for the acetabular component
  • that surgeons should ensure that it was not positioned to interfere with the iliopsoas tendon
  • that it was possible both to detect prominence and correct it. 

They were both, in fact, critical of the orientation of the acetabular component but disagreed as to whether it was outside the reasonable range to amount to a breach of duty. Therefore, the key issue was whether the result in this case, though poor, fell below an acceptable standard.

In his revision practice, Mr Manktelow encountered acetabular components left prominent after primary repairs. This amounted to an error and he disapproved of it. But he accepted that there was a body of surgeons who would achieve the same poor result. He offered no justification or rationale for them doing so. And in Mr Chatterji's evidence it was an entirely avoidable complication. This lack of rationale for an avoidable result persuaded the judge to prefer the evidence of the less specialist expert. The judge commented, "I was left with the impression that Mr Manktelow's justification for asserting that there was no breach of duty was because he said so".

Two key points about expert witness evidence

This raises two points about expert evidence. The first is that, in many cases, it is an advantage to have the more specialist expert. That is not always the case: in reporting on breach of duty – there is sometimes a risk of a specialist judging a generalist by too high a standard. But, in this case, it was the more specialist surgeon who was accepting of a lower standard. 

The second is that, however experienced and specialist the expert, they need to give a clear rationale for their view. Good expert evidence is based on transparent and logical reasoning. As a judge said in another case, "Experts' opinions, if they are to be accorded any weight, need to be supported by a transparent process of reasoning" [2].

Breach of duty in clinical negligence

The Bolam test of course defines breach of duty about the conduct of orthopaedic surgery. Conduct fails the test if it falls outside that of a reasonable and responsible body of orthopaedic surgeons. The case of Bolam[3] itself defined negligence by a negative: what was not negligent. In the words of McNair J (perhaps assuming all doctors were male), "a man is not negligent, if he is acting in accordance with such a practice, merely because there is a body of opinion who would take a contrary view".

Here the judge found that there were two bodies of opinion. One – represented by both experts – was that a surgeon should ensure so far as possible that the acetabular component was not placed prominently so as to interfere with the iliopsoas tendon. The contrary view – represented by the defendant – was that it was acceptable to do so.  On the face of it, the Bolam defence was made out, and the surgeon's error fell short of negligence.

Bolam and Bolitho

However, the Bolam test was qualified by the later case of Bolitho[4]. The Bolitho qualification says that, to amount to a responsible body, its exponents must demonstrate its logical basis. In this case, the judge found no logical basis for failing to take steps that would identify and correct an acetabular component that was prominent. There was no fine balancing of risks here. There was simply an error that could be avoided. He, therefore, found that, although the contrary view was common to a body of surgeons, it was not that of a reasonable and responsible body. The practice was a breach of duty, and the claimant succeeded.

A slightly odd feature of the judgment is that the judge specifically rejected the submission of the defendant's leading counsel that the claimant was required to rely on the Bolitho qualification. The evidence suggested that there were two schools of thought. To succeed, the claimant needed to show that one was not logical. The judge said, "In my view, both Bolam and Bolitho require the court to examine the different schools of thought and to ask itself whether the school of thought relied on by the defendant can demonstrate that its exponents' opinion has a logical basis". Yet the defendant's submission appears to have been entirely correct. Bolam does not refer to whether the practice of a responsible body is logical. That is the refinement added by Bolitho.


Paul Sankey is a clinical negligence solicitor and Partner at Enable Law. Read Paul's other recent articles on 'Expert witness duties: independence and impartiality again' and 'Expert witnesses: lessons from recent cases'.

[1] [2020] EWHC 1351 (QB)
[2] Hirtenstein and Il Sole Ltd v Hill Dickenson [2014] EWHC 2711 (Comm)
[3] Bolam v Friern Hospital Management Committee [1957] 1 WLR 583
[4] Bolitho v City and Hackney Health Authority [1996] 4 All ER 771

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