§ GUIDE · INFORMED CONSENT

Consent claims
after Montgomery.

Since 2015 the law has asked what a reasonable patient would want to know, not what doctors chose to tell. A consent claim can succeed even where the operation itself was done well. But the judgments below show that it can also fail, and why the paperwork matters so much.

The leading case

[2015] UKSC 11

Parsons agreed damages

£1,300,000

Consent claims here

5

Of which failed

2

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§ THE RULE

Material risks, and reasonable alternatives.

In Montgomery v Lanarkshire Health Board [2015] UKSC 11 a diabetic mother of small stature was not told of the roughly 10 per cent risk of shoulder dystocia in a vaginal birth, or offered a caesarean. Her son was born with cerebral palsy. The Supreme Court held that doctors must tell patients about material risks and reasonable alternatives: a risk is material if a reasonable person in the patient's position would attach significance to it, or if the doctor should know this particular patient would.

The decision replaced the old approach under which the profession decided what patients needed to hear. It underpins most modern consent claims.

§ CONSENT IS NOT A ONE-OFF

When the plan changes, the conversation has to happen again.

Parsons v Isle of Wight NHS Trust [2023] EWHC 3115 (KB)

Before bowel cancer surgery, anaesthetists made three failed epidural attempts while the patient was awake and then seven more after putting her under anaesthetic; one pierced her spinal cord. The judge held she should have been asked before the unconscious attempts and offered alternatives, and that this failure caused the injury. Agreed damages of £1.3 million followed.

HQA v Newcastle upon Tyne Hospitals [2025] EWHC 2121 (KB)

A high-risk repeat heart operation. The judge found breaches in planning and in consent: the patient should have been advised in an outpatient appointment beforehand, and told that the femoral vessels could be exposed in advance to reduce the harm from a known risk. She would still have gone ahead, but with that precaution taken.

§ WHY CONSENT CLAIMS FAIL

A signed form and a leaflet naming the risk are hard to get past.

Tosh v Gupta [2025] EWHC 2025 (KB)

The claimant said the risk of anal stenosis after her haemorrhoidectomy was never explained and non-surgical options were not discussed. The judge found the alternatives were discussed and the risk was disclosed on the consent form and in the information leaflet. Claim dismissed.

Deakin-Stephenson v Behar and Chelsea and Westminster [2024] EWHC 2338 (KB)

After emergency surgery for perforated diverticulitis the claimant said she was not properly consented and had asked for a colorectal referral. The judge found none of it proved and dismissed the claims against both the surgeon and the trust.

§ CAUSATION IN CONSENT CASES

You must show the warning would have changed your decision.

Proving that a risk was not explained is only half the claim. The court then asks what you would have done if it had been. In Parsons the judge found the claimant would have chosen differently, so the whole agreed sum was recoverable. In HQA the judge found the patient would still have proceeded, though with the extra precaution, which shapes what the consent breach can be said to have caused. Honest evidence about what you would have decided, and why, is central.

§ THE JUDGMENTS BEHIND THIS GUIDE

Five consent judgments.

The Supreme Court decision that set the test, two claims that succeeded on consent, and two that failed on the evidence.

Claimant succeeded

Montgomery v Lanarkshire Health Board

[2015] UKSC 11·2015·Appeal decision

A diabetic mother of small stature was not told of the roughly 10 per cent risk of shoulder dystocia in a vaginal birth or offered a caesarean, and her son was born with cerebral palsy. The Supreme Court held doctors must tell patients about material risks and reasonable alternatives, replacing the old doctor-knows-best approach to consent.

Since Montgomery, a claim can succeed where a patient was not warned of a risk that a reasonable person in their position would consider significant, even if some doctors would not have mentioned it. It underpins most modern consent-based negligence claims.

Claimant succeeded£1.3M

Parsons v Isle of Wight NHS Trust

[2023] EWHC 3115 (KB)·2023·Liability decided at trial

Before bowel cancer surgery, anaesthetists made three failed epidural attempts while the patient was awake and then seven more after putting her under anaesthetic, one of which pierced her spinal cord. Ritchie J held the anaesthetist should have obtained her informed consent before the unconscious attempts and offered alternatives, and that this failure caused the injury.

Consent is not a one-off: when a procedure changes course (here, moving to unconscious epidural attempts), the patient must be told of the options and risks again. The full agreed £1.3m followed from that single consent failure.

Claimant succeeded

HQA v Newcastle-upon-Tyne Hospitals NHS Foundation Trust

[2025] EWHC 2121 (KB)·2025·Liability decided at trial

A 25-year-old with congenital heart disease suffered a severe brain injury when her aorta was cut during a high-risk repeat sternotomy and it took around 24 minutes to get her onto full bypass. The judge found the surgeon should have exposed the femoral vessels in advance (saving around 13 minutes) and that consent was deficient; she would still have gone ahead with the operation, but with that precaution taken.

Surgeons planning a known high-risk operation must take reasonable precautions beforehand and tell the patient about them; a court can find negligence in planning and consent even where the intra-operative error itself was not negligent.

Claim failed

Julia Tosh v Vivek Gupta

[2025] EWHC 2025 (KB)·2025·Liability decided at trial

The claimant developed anal stenosis after a private haemorrhoidectomy and argued her haemorrhoids had been over-graded, non-surgical options were not discussed and the stenosis risk was not explained. The judge found the grading was correct, alternatives were discussed and the risk was disclosed on the consent form and in the information leaflet, so the claim was dismissed.

Documented consent, including a signed form and a written leaflet naming the specific complication, can be decisive in defeating a Montgomery consent claim.

Claim failed

Philippa Caroline Deakin-Stephenson v Nebil Behar and Chelsea and Westminster Hospital NHS Foundation Trust

[2024] EWHC 2338 (KB)·2024·Liability decided at trial

Admitted with perforated diverticulitis, the claimant had a laparoscopic washout and deteriorated about 36 hours later, needing an emergency Hartmann's procedure with a stoma and intensive care. She alleged she had asked for a colorectal referral, was improperly moved to private care and was not properly consented, but the judge found none of this proved and dismissed the claims against both the surgeon and the trust.

Consent disputes turn on evidence of what was actually discussed; where the records and the surgeon's account show the alternative procedure was explained, a claim based on inadequate consent is likely to fail.

Browse the whole case library →

Contains information licensed under the Open Justice - Licence v2.0. Judgments from Find Case Law, The National Archives. Summaries are ours; amounts only where printed in the judgment.

§ QUESTIONS

Common questions

Can I claim if the operation was done properly but I was not warned of the risk?

Yes, potentially. Since Montgomery, failing to explain a material risk or a reasonable alternative is a breach of duty in itself. You still have to show that you would have made a different decision had you been told, and that the risk materialised.

What counts as a material risk?

One that a reasonable person in your position would attach significance to, or that the doctor should have realised you in particular would care about. It is not just about percentages: a small risk of a devastating outcome can be material.

I signed a consent form. Does that end the claim?

Not automatically, but it is strong evidence. In Tosh v Gupta the form and the leaflet naming the complication were decisive. The question is what you were actually told and given, not only what you signed.

Do I have to be consented again if the plan changes during treatment?

Where a procedure moves to a different approach, as in Parsons when epidural attempts continued under anaesthetic, the court expected the options and risks to be discussed again beforehand.

Does Montgomery apply in England if it was a Scottish case?

Yes. It was an appeal from Scotland but the Supreme Court set out the consent test for the whole of the UK, and the English courts apply it.

§ MORE GUIDES

Plain answers to the other questions people ask.

Why claims fail →

Eleven real judgments where the claim failed, and what each one teaches about proving breach of duty, causation and loss in a medical negligence claim.

Payout examples →

UK medical negligence payout examples by claim type, typical compensation ranges, and what decides the amount. Then check your own claim free.

Fatal negligence payouts →

What compensation after a death caused by medical negligence can include: the bereavement award, dependency, funeral costs and the estate's claim.

Time limits →

The 3-year time limit for medical negligence claims, the date-of-knowledge rule, and the exceptions for children, mental capacity and fatal claims.

How long claims take →

How long medical negligence claims really take, stage by stage, using official NHS Resolution timing data — and what slows a claim down.

NHS payout data →

Official NHS Resolution figures, band by band, for 2024/25.

This guide is general information about the law in England and Wales, not legal advice about your case. ClaimGavel is run by Costart Projects Ltd on behalf of Tomlin & Partners, a specialist medical negligence firm regulated by the SRA. The free assessment on this page is an AI overview to show you roughly where you stand; a solicitor confirms the position in a free, no-obligation conversation.