Consent, causation and Chester  – the Court of Appeal examines the modified test in Duce v Worcestershire Acute Hospitals NHS Trust [2018] EWCA Civ 1307

This blog is by Vanessa Cashman of 12 King’s Bench Walk.


The claimant underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy in order to treat extremely painful and heavy periods. She was 41 years old at the time.

The operation was performed non-negligently on 25 March 2008. Following surgery the claimant developed Chronic Post-Surgical Pain as a result of nerve damage. The issues were whether she was properly consented in respect of the risk of post-operative pain and whether she could establish causation.

The facts

In a consultation on 4 March 2008 the claimant met with a consultant gynaecologist who recorded that the claimant was sure she wanted to have a hysterectomy. The notes concluded with “risks explained”.

On the morning of surgery on 25 March 2008 the claimant had been consented by a registrar, who warned her about post-operative pain normally associated with surgery. It was accepted that the registrar did not warn the claimant about developing chronic pain or neuropathic pain following surgery. The anaesthetist also agreed that she too would have only warned the claimant of normal post-operative pain.

The RCOG guidance did not refer to a risk of chronic, long-term or neuropathic pain. The experts agreed that CPSP was not common knowledge amongst gynaecologists in 2008.

First instance

The judge at first instance, HHJ Worster, found that there was no duty to warn a patient of the risk of chronic or neuropathic pain. Such requirement did not follow the RCOG guidance and the understanding of such pain by gynaecologists in 2008 did not justify the imposition of a duty to warn of it.

He went on to find that even if the claimant had been warned of the risk, she would still have opted to undergo the operation on the day she did.

Grounds of appeal

The claimant appealed both in relation to breach of duty and causation. The grounds of appeal on the former aspect were that the judge had failed to apply the Montgomery test of materiality and instead had applied the Bolam test. In respect of causation, it was said that the judge failed to apply the Chester v Afshar test or, alternatively, that he misapplied the test for causation and had he applied the correct test, causation would have been made out on the facts.

Breach of duty

On appeal, it was held that that judge did not consider the materiality test because he had already found that gynaecologists were not aware of the relevant risks at the applicable time. Hamblen LJ reminds us of the two-fold test in respect of the first limb of Montgomery (which is that the doctor must take reasonable care to ensure that the patient is aware of any material risks and of any reasonable alternative treatment) as follows:

  1. What risks were or should have been known to the medical professional. This is a question for the experts;
  2. Whether the patient should have been told about such risks by reference to whether they were material. This is question for the Court, although expert evidence is likely to assist.

Therefore the judge did not have to consider materiality because the evidence was that the risks of chronic/neuropathic pain were not known to the relevant treating doctors; the claim thus failed at the first hurdle and did not proceed to the second. That was a finding which the judge was entitled to make and there was no arguable challenge to it.


The claimant submitted that she did not have to prove that she would not have had the operation. Instead, she argued that Chester was authority for the proposition that if the injury was intimately involved with the duty to warn, that duty was owed and the injury was the product of the very risk the patient should have been warned about, causation is made out in consent cases.

The Court of Appeal considered that this would amount to a wholesale disapplication of conventional causation principles in consent cases. Claimants still have to demonstrate a “but for” causative effect of the breach of duty. In Chester it was appropriate that the test was modified because of the very unusual circumstances of the case (that the claimant had established that she would not have consented to the operation on the date she did and that the risk which eventuated was so small that the risk of it occurring on a subsequent occasion was also very small). The Court of Appeal remind us that Chester established an exceptional principle of causation which must be pleaded if it is to be argued.

The final ground of appeal on causation was against the factual finding that the claimant would still have proceeded with the operation on the basis that she chose the treatment predominantly to relieve her pain. Therefore had she been warned of a further and different type of pain, she would not have chosen to undergo the operation. The Court of Appeal held that the judge’s finding on this could not be challenged.

Ultimately, therefore, the appeal was dismissed on all grounds.


This principal importance of this case is the way in which the Court of Appeal have interpreted Chester and considered its future application. The interpretation of Chester in this case is restrictive and the tenor of the judgments (in particular, that of Leggatt LJ) is that Chester is highly problematic in respect of ordinary causation principles, the scope of the duty of care and in respect of the burden of proof. Leggatt LJ’s view is that Chester was decided for policy reasons, which in themselves are flawed. He said, at [88], that the right to make an informed choice is not a right that is traditionally protected by the tort of negligence; the purpose of the tort is to protect a person from being exposed to injury through another’s carelessness. In consent cases the duty is not to protect the claimant from a risk of injury; the duty is to enable the claimant to decide whether or not that risk is acceptable to her. He commented that the fact that a claimant has difficulty in proving what she would have done had she been warned of the risk (such difficulty being caused by the defendant’s negligence in failing to warn her of the risk) does not normally justify a reversal of the burden of proof. He concluded by saying that these matters may be ripe for further consideration by the Supreme Court.

It is likely that Chester principles will only be applicable in cases where the claimant can only establish that s/he would not have undergone the operation or treatment at the time at which they did and that the relevant risk was identical at a later time. If the claimant can establish that s/he would not have undergone the treatment at all then traditional “but for” causation can be made out. If the claimant cannot establish that she would have deferred the operation or that she would not have had it at all, the claim will fail.

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