The Supreme Court decision that set the test, two claims that succeeded on consent, and two that failed on the evidence.
Claimant succeeded
[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
[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
[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
[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
[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.
Claimant succeeded£298,617
[2023] EWHC 42 (KB)·2023·Liability and damages decided at trial
An engineer had a then-novel transanal rectal cancer operation without being told of the risks to sexual, urinary and bowel function, and was consented on the day of surgery. The judge found the trust failed to follow NICE guidance, accepted he would have chosen a conventional laparoscopic operation, and awarded £298,616.73.
Consent taken on the day of surgery without explaining material risks or alternatives can found a claim even if the surgery itself was competently done. New or learning-curve procedures need particularly careful counselling.
Claim failed
[2020] EWHC 310 (QB)·2020·Liability decided at trial
Ms Pepper argued she had only agreed to a Whipple's operation if an intra-operative biopsy proved cancer, and the biopsy was negative. The judge found she had consented to surgery if the biopsy was positive or the pancreas looked suspicious, that intra-operative biopsies are known to be unreliable, and dismissed the claim.
Consent disputes turn on what was actually agreed before surgery, and courts give weight to contemporaneous notes and what a reasonable patient would have decided. A negative result on an unreliable test does not by itself make surgery negligent.
Claimant succeeded
[2017] EWHC 497 (QB)·2017·Liability decided at trial
Mrs Thefaut was told her disc operation had about a 90% chance of curing her leg pain and would probably settle her back pain, with tiny risks. Green J found the real prospects and risks were materially different, that she was not properly informed, and that the claim succeeded on consent although the surgery itself was not negligently performed.
Overstating the benefits or understating the risks of surgery can breach the Montgomery duty even when the operation is done competently. Patients must be given a fair picture including the option of not operating.
Claim failed
[2021] EWHC 643 (QB)·2021·Liability decided at trial
The executors of Mrs Neill argued her surgeon should have enlarged the aortic root to fit a larger valve rather than implant a 19mm mechanical valve, and failed to warn her about that option. Eady J found the valve choice was not negligent and, although the possibility of root enlargement should have been mentioned, it would have made no difference to her decision.
A consent failure only leads to compensation if the patient would have made a different choice with proper information. Surgical decisions supported by a responsible body of opinion are not negligent just because another surgeon would have done differently.
Claimant succeeded
[2020] EWHC 2902 (QB)·2020·Liability decided at trial
A 79-year-old with macular degeneration was persuaded to have an intraocular lens implant in her better eye without proper informed consent, then developed raised eye pressure that the surgeon left untreated for five weeks. Stacey J found the surgeon negligent both in consenting and in delaying laser treatment, causing total blindness in that eye.
Private eye surgeons must obtain genuinely informed consent and act promptly on post-operative complications. A delay that materially contributes to permanent damage is enough for liability even if some harm had already occurred.
Claim failed
[2016] EWHC 331 (QB)·2016·Liability decided at trial
A teenager with back pain had a lumbar microdiscectomy and afterwards developed cauda equina syndrome. She argued the surgeon should have sought a second opinion and consented her properly; the court rejected the criticisms and found the CES was a non-negligent complication.
Cauda equina syndrome can be a recognised complication of spinal surgery rather than evidence of negligence. Consent claims fail if the court accepts the surgeon gave adequate advice.