[2025] EWHC 2025 (KB)

[7]…would not have undergone surgery three days after her first consultation with Mr Afshar but would, very understandably, have wished to discuss the matter with others and explore other options. But he did not find (and was not invited to find) that she would probably not have undergone the surgery or that there was any way of minimising the small degree of risk inherent in surgery.

…But how can causation be established when, as in this case, the patient would not have refused absolutely there and then and for ever to undergo the operation if told of the risks but would have postponed her decision until later?

The problem is rendered all the more acute in this case by the fact that the failure to warn cannot be said in any way to have increased the risk of injury. The risk was inherent in the operation itself. It was described by Miss Chester's expert witness, Mr Firth, as “the terror of neurosurgery.” The evidence indicated that it was also liable to occur at random, irrespective of the degree of care and skill with which the operation was conducted by the surgeon. This means that the risk would have been the same whenever and at whoever's hands she had the operation. It can be said that Miss Chester would not have suffered her injury “but for” Mr Afshar's failure to warn her of the risks, as she would have declined to be operated on by him on 21 November 1994. But it is difficult to say that his failure was the effective cause of the injury.

I would accept that a solution to this problem which is in Miss Chester's favour cannot be based on conventional causation principles. The “but for” test is easily satisfied, as the trial judge held that she would not have had the operation on 21 November 1994 if the warning had been given. But the risk of which she should have been warned was not created by the failure to warn. It was already there, as an inevitable risk of the operative procedure itself however skilfully and carefully it was carried out. The risk was not increased, nor were the chances of avoiding it lessened, by what Mr Afshar failed to say about it. As Professor Honoré in his note “Medical non-disclosure, causation and risk: Chappel v Hart” (1999) 7 Torts LJ 1 , 4 has pointed out, to expose someone to a risk to which that person is exposed anyhow is not to cause anything.