Category: Insurance case law · Reviewed by Al Jabbar, Broker · Specialist Risks · Last reviewed June 2026
The House of Lords decision qualifying Bolam by holding that a body of professional opinion will not exonerate a defendant unless the court is satisfied it has a logical basis.
Patrick Bolitho was a two-year-old child who was admitted to St Bartholomew’s Hospital on 11 January 1984 with breathing difficulties caused by croup. He appeared to recover but on 16 January suffered two episodes of acute respiratory distress. On each occasion the ward sister telephoned the senior paediatric registrar, Dr Horn, who failed to attend the patient. A short time later Patrick suffered total respiratory failure, sustained cardiac arrest and was severely brain-damaged. He died some years later.
It was admitted that Dr Horn was negligent in failing to attend. The critical issue was causation. Had Dr Horn attended, would she have intubated the child? If she would have intubated, on the medical evidence the cardiac arrest would have been avoided. If she would not have intubated, the negligent failure to attend made no causative difference to the outcome.
Dr Horn gave evidence that, even if she had attended, she would not have intubated Patrick at the relevant time. The trial judge had therefore to consider the further question: if Dr Horn would not have intubated, would that hypothetical decision itself have been negligent? That required application of the Bolam test to the hypothetical decision.
The defendants called five distinguished experts who supported a decision not to intubate; the claimant called three who said intubation was mandatory. The trial judge accepted that there were two responsible bodies of professional opinion and, applying Bolam, held that the defendants escaped liability. The Court of Appeal upheld that decision by a majority. The claimant appealed to the House of Lords, arguing that the Bolam test allowed the medical profession in effect to set its own standard of care.
The principal issue was the proper application of the Bolam test where a body of professional opinion supported the conduct of a defendant but the court considered that view to be open to logical or rational challenge. Specifically, was the existence of any responsible body of professional opinion supporting the defendant conclusive, or was the court entitled to scrutinise the reasoning underpinning that opinion?
A subsidiary causation issue concerned how, in a clinical negligence case where the negligence is an omission, the court determines what would have happened but for the omission, particularly where the relevant decision involved professional judgement.
The House of Lords unanimously dismissed the appeal on the facts but used the occasion to refine the Bolam principle in a way that has had wide-ranging consequences for professional negligence claims.
Lord Browne-Wilkinson, giving the leading speech, accepted that the trial judge had been entitled to find that the defence experts represented a responsible body of opinion and that, on the evidence, their views were not capable of being characterised as illogical. The appeal therefore failed on its facts.
However, his Lordship held that the use of the words responsible, reasonable and respectable in describing the body of opinion in Bolam imported the requirement that the opinion had a logical basis. The court had to be satisfied that the experts had directed their minds to the comparative risks and benefits and had reached a defensible conclusion. It would only be in rare cases that a court would conclude that the views of competent medical experts were not capable of withstanding logical analysis, but the court retained the power to do so.
The decision thus preserved the central thrust of Bolam — that there can be more than one acceptable approach in a profession — while removing the absolute deference that some had read into Bolam. Professional opinion must be supported by reasoned analysis; mere assertion or longstanding habit is not enough.
A professional defendant is not negligent merely by reason of having acted in accordance with a practice supported by a body of professional opinion, unless that body of opinion is capable of withstanding logical scrutiny. The court is the ultimate arbiter of whether a body of opinion is responsible, reasonable and respectable, and may reject it where it cannot be shown to have a logical basis weighing the comparative risks and benefits of the courses available.
Bolitho has profound importance for the assessment of professional indemnity claims because it changed the centre of gravity of the Bolam defence. Before Bolitho, insurers and defendants could often defeat a claim simply by adducing expert evidence that some competent professionals would have done the same thing. After Bolitho, the court actively interrogates the reasoning behind that evidence; bare assertion will not do.
For PI insurers this has several practical consequences. First, expert selection in defending PI claims is critical: the expert must be able to articulate the logical basis for the body of opinion they say supports the insured, not merely assert its existence. Second, contemporaneous documentation by the insured of the reasons for choosing one course over another has acquired greater evidential value because it demonstrates that risks and benefits were weighed at the time. Third, the case has encouraged the development of professional guidance, checklists and protocols within professions because compliance with such guidance provides a ready logical basis for the body of opinion supporting the defendant.
Bolitho is also influential outside the medical sphere. It is regularly cited in claims against solicitors, accountants, valuers, financial advisers and IT professionals. In any PI case where the defence is that the insured did what others in the profession would do, Bolitho ensures the court will examine whether that practice itself is defensible.
By Matt Bartlett, Director, on 2026-06-06. Next review: 2026-12-06.
This entry is part of the Apex Insurance Wiki. Last reviewed by Matt Bartlett on 2026-06-06. Apex Insurance Brokers Limited, FCA FRN 724952, Companies House 07014570. Not regulated advice — consult your broker on your specific position.
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