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Are there cases of clinical negligence in which the Bolam test has no application?
We know that in the field of informed consent the Supreme Court in Montgomery v Lanarkshire recently emphasised that the Bolam test is not an appropriate yardstick for ensuring that patient autonomy is respected. Now, in Muller v King's College Hosptial NHS Foundation Trust  EWHC 128 (QB) Kerr J has addressed the applicability of the Bolam test to cases of purely diagnostic error, where there is no question of the exercise of professional judgment in relation to management or treatment.
The Claimant alleged that there was a negligent error by a histopathologist in reporting what was a biopsy of a malignant melanoma as a non-malignant lesion.
Defendant's counsel submitted that Bolam should be applied "unvarnished". The admitted error in reporting:
"... could easily be made by a histopathologist acting with reasonable competence, i.e. with reasonable skill and care. Mr Gibson submitted that Dr Foria's expert opinion was founded on acceptable reasoning and not outside the bounds of respectable medical opinion.
"Mr Gibson submitted, therefore, that Professor Wright's contrary view - that Dr Goderya committed a plain breach of duty - should not be preferred; Dr Foria's opinion was sufficient to exonerate Dr Goderya from the charge of negligence. Applying the Bolam doctrine, the court should not choose between these opposing experts' views; Dr Foria's view should carry "substantial weight" and should not be rejected unless Professor Wright's evidence cast it in "such an altogether negative light that it should be rejected" (per Green J in C. v. North Cumbria University Hospitals NHS Trust, at paragraphs 25(i) and 73)."
[paras 44 and 45]
In contrast Claimant's counsel argued
"that the application of the Bolam principle did not provide the answer here. He proposed that the governing authority was the Court of Appeal's decision in Penney v. East Kent Health Authority  PNLR 323, in which Lord Woolf MR gave the judgment of the court. That case, he pointed out, was like this one a case of interpreting objective data wrongly.
"He submitted that Penney showed that the court must determine the objective facts about what pathological features were there to be seen on the slides - which in the present case is a matter of agreement - and then decide for itself whether, in the light of the differing experts' views, the misdiagnosis was one that must have been made without the use of reasonable skill and care. The court could not abdicate its responsibility to resolve the conflict of expert opinion by resorting to the Bolam-derived notion of a respectable body of medical opinion."
[46 and 47]
The Judge considered the context in which Bolam and other cases had been decided and concluded at 
"In a case involving advice, treatment or both, opposed expert opinions may in a sense both be "right", in that each represents a respectable body of professional opinion. The same is not true of a pure diagnosis case such as the present, where there is no weighing of risks and benefits, only misreporting which may or may not be negligent. The experts expressing opposing views on that issue cannot both be right. And the issue is, par excellence a matter for the decision of the court, which should not, as a matter of constitutional propriety, be delegated to the experts."
"I am bound by the law as it currently stands, to approach that issue by reference to a possible invocation of the Bolitho exception. I must not, therefore, reject Dr Foria's view unless I am persuaded that it does not hold water, in the senses discussed in Lord Browne-Wilkinson's speech in Bolitho and developed in other cases: that is to say, if it is untenable in logic or otherwise flawed in some manner rendering its conclusion indefensible and impermissible." 
This might point the way to future appellate consideration (perhaps not in this particular case) of the approach that should be taken to cases involving errors of reporting and diagnosis.