Bolitho v City and Hackney Health Authority [1998] AC 232 is the House of Lords decision that put a limit on the deference owed to expert opinion under the Bolam test. The facts concerned the death of a two-year-old child, Patrick Bolitho, who suffered cardiac arrest in hospital after a junior doctor and senior registrar failed to attend and intubate him. The defence relied on expert evidence that intubation would not have been appropriate in any event, and that a responsible body of paediatric opinion would have managed the child the same way.
Lord Browne-Wilkinson, giving the leading speech, accepted that the Bolam principle still applied: a professional is not negligent if they act in accordance with a practice accepted as proper by a responsible body of opinion in that field. He added a qualification. The court must be satisfied that the body of opinion relied on rests on a logical basis. Where expert evidence cannot withstand logical analysis, the judge is entitled to hold that the body of opinion is not reasonable or responsible, and to reject it.
Bolitho does not displace the Bolam framework. A professional whose work conforms to a responsible body of opinion will still ordinarily escape liability. What Bolitho changes is the question the judge has to ask before accepting that body of opinion as a defence. The court now examines whether the opinion is internally consistent, whether it has weighed the risks and benefits, and whether it can be defended in light of the evidence available at the time.
Lord Browne-Wilkinson said cases where a judge can reject an apparently respectable body of expert opinion will be rare. The threshold is logical defensibility, not whether the judge would have decided the question differently. But the door is open, and post-Bolitho case law has walked through it in fields well beyond clinical negligence. For more on the underlying test see Bolam test; for the formulation as a free-standing test see Bolitho test.
The principle now runs across the whole of professional negligence law. "Everyone did it" is no longer a complete answer where the practice ignored published warnings, departed from updated guidance, or rested on assumptions that should have been re-examined. Courts apply Bolitho to surveyors, architects, solicitors, accountants, financial advisers and engineers as readily as to clinicians. For the surveyor-specific application see Bolam test for surveyors and valuers.
A valuer faces a claim arising from a 2018-2019 high-rise valuation that did not address external wall fire performance. The defence expert says valuers commonly accepted no due diligence on EWS1 forms in that period. Under pure Bolam the analysis might stop there. Under Bolitho the court asks whether that body of opinion was logically defensible given what was already known about combustible cladding after the Grenfell Tower fire in June 2017, and given the lender guidance circulating before EWS1 was formalised.
An architect is sued in connection with the specification of ACM PE cladding on a residential block designed before June 2017. The defence expert says specifying ACM PE was common practice across the sector at the time. Bolitho asks whether that body of opinion was logically defensible in light of published fire test data, manufacturer technical statements and earlier overseas cladding fires. A common practice that ignored a known fire performance issue is the kind of opinion a court can decline to accept.
A conveyancer is sued for not commissioning environmental searches on a purchase of a former industrial site. The defence expert says many conveyancers did not routinely search environmental data at the time. Bolitho asks whether ignoring contamination liabilities that were already established in case law and statute was defensible. The court is entitled to reject a peer-practice defence that does not engage with the known risk.
For firms taking out professional indemnity cover, Bolitho is the reason a practice that was "normal at the time" is not always a safe harbour. Insurers and defence solicitors now expect to test peer-practice evidence against the question of logical defensibility. Files that show the professional engaged with published guidance, weighed risks, and recorded the reasoning behind a departure from emerging standards are easier to defend than files that simply rely on what others were doing.
Apex arranges PI cover for architects, surveyors and solicitors, and the Bolitho qualification informs how claims defences are built across each of those sectors.
Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Firm reference number 724952. This entry is general information, not advice on any particular policy.