Gregg (FC) (Appellant) v. Scott (Respondent)
35. The position with medical negligence claims is different. The patient's actual condition at the time of the negligence will often be determinative of the answer to the crucially important hypothetical question of what would have been the claimant's position in the absence of the negligence. Hotson v East Berkshire Heath Authority  AC 750 is an instance of this. The relevant factual question concerning Stephen Hotson's condition immediately prior to the negligence was whether his fall from the tree had left sufficient blood vessels intact to keep his left femoral epiphysis alive. The answer to this question of actual fact ipso facto provided the answer to the vital hypothetical question: would avascular necrosis have been avoided if Stephen Hotson's leg had been treated promptly? The answer to the first question necessarily provided the answer to the second question, because the second question is no more than a mirror image of the first. Built into the formulation of the first question was the answer to the second question.
36. This is not always so. Many cases are not so straightforward. Sometimes it is not possible to frame factual questions about a patient's condition which are (a) susceptible of sure answer and also (b) determinative of the outcome for the patient. As already noted, limitations on scientific and medical knowledge do not always permit this to be done. There are too many uncertainties involved in this field.
37. The present case is a good example. Identifying the nature and extent of Mr Gregg's cancer at the time of the mistaken diagnosis (the first question), so far as this could be achieved with reasonable certainty, did not provide a simple answer to what would have been the outcome had he been treated promptly (the second question). There were several possible outcomes. Recourse to past experience in other cases, that is statistics, personalised so far as possible, was the best that could be done. These statistics expressed the various possible outcomes in percentage terms of likelihood.
38. Thus, for present purposes medical negligence cases fall into one or other of two categories depending on whether a patient's condition at the time of the negligence does or does not give rise to significant medical uncertainty on what the outcome would have been in the absence of negligence. The Hotson case was in one category. There was no significant uncertainty about what would have happened to Stephen Hotson's leg if treated promptly, once his condition at the time of the negligence has been determined on the usual probability basis. The present case is in the other category. Identifying Mr Gregg's condition when he first visited Dr Scott did not provide an answer to the crucial question of what would have happened if there had been no negligence. There was considerable medical uncertainty about what the outcome would have been had Mr Gregg received appropriate treatment nine months earlier.
39. In the Hotson case the House left open the legal position in the 'Gregg' type of case. The House held that factual issues concerning Stephen Hotson's medical condition at the time of the negligence should be answered on the conventional all-or-nothing balance of probability basis. But Lord Bridge of Harwich noted there may be cases, particularly medical negligence cases, where causation is 'so shrouded in mystery' that the court can only measure statistical chances. He added that there are 'formidable difficulties' in the way of accepting the 'superficially attractive analogy' between the principle applied in cases such as Chaplin v Hicks  2 KB 786 and Kitchen v Royal Air Force Association  1 WLR 563 and the principle of awarding damages in medical negligence cases for the lost chance of a better medical result: Hotson v East Berkshire Heath Authority  1 AC 750, 782, 783; see also Lord Mackay of Clashfern at pp 789-790.
40. I respectfully agree there may be difficulty in applying the 'diminution in prospects' approach in the Hotson type of case, because this would involve departing from the established all-or-nothing balance of probability approach used to decide disputed questions of past actual fact (what was the patient's condition at the time of the negligence). It may not be altogether easy to carve out an exception for medical negligence cases without, in Professor Andrew Burrow's phrase in 'Remedies for Tort and Breach of Contract', 3rd edition, p 61, 'shattering the conventional approach altogether'.
41. That difficult question does not arise in the present case. That question is to be pursued, if at all, on another occasion. The question in the present, 'Gregg' type of case concerns how the law should proceed when, a patient's condition at the time of the negligence having been duly identified on the balance of probability with as much particularity as is reasonably possible, medical opinion is unable to say with a reasonable degree of certainty what the outcome would have been if the negligence had not occurred.
42. In principle, the answer to this question is clear and compelling. In such cases, as in the economic 'loss of chance' cases, the law should recognise the manifestly unsatisfactory consequences which would follow from adopting an all-or-nothing balance of probability approach as the answer to this question. The law should recognise that Mr Gregg's prospects of recovery had he been treated promptly, expressed in percentage terms of likelihood, represent the reality of his position so far as medical knowledge is concerned. The law should be exceedingly slow to disregard medical reality in the context of a legal duty whose very aim is to protect medical reality. In these cases a doctor's duty to act in the best interests of his patient involves maximising the patient's recovery prospects, and doing so whether the patient's prospects are good or not so good. In the event of a breach of this duty the law must fashion a matching and meaningful remedy. A patient should have an appropriate remedy when he loses the very thing it was the doctor's duty to protect. To this end the law should recognise the existence and loss of poor and indifferent prospects as well as those more favourable.
43. Application of the all-or-nothing balance of probability approach in the 'Gregg' type of cases would not achieve this object. In such cases the law should therefore put aside this approach when considering what would have happened had there been no negligence. It cannot be right to adopt a procedure having the effect that, in law, a patient's prospects of recovery are treated as non-existent whenever they exist but fall short of 50%. If the law were to proceed in this way it would deserve to be likened to the proverbial ass. Where a patient's condition is attended with such uncertainty that medical opinion assesses the patient's recovery prospects in percentage terms, the law should do likewise. The law should not, by adopting the all-or-nothing balance of probability approach, assume certainty where none in truth exists: see Deane J in Commonwealth of Australia v Amann Aviation Pty Ltd (1991) 66 ALJR 123, 147. The difference between good and poor prospects is a matter going to the amount of compensation fairly payable, not to liability to make payment at all. As Dore J said in Herskovits v Group Health Cooperative of Puget Sound (1983) 664 P 2d 474, 477:
44. The way ahead must surely be to recognise that where a patient is suffering from illness or injury and his prospects of recovery are attended with a significant degree of medical uncertainty, and he suffers a significant diminution of his prospects of recovery by reason of medical negligence whether of diagnosis or treatment, that diminution constitutes actionable damage. This is so whether the patient's prospects immediately before the negligence exceeded or fell short of 50%. 'Medical uncertainty' is uncertainty inherent in the patient's condition, uncertainty which medical opinion cannot resolve. This is to be contrasted with uncertainties arising solely from differences of view expressed by witnesses. Evidential uncertainties of this character should be resolved in the usual way.
45. This approach would represent a development of the law. So be it. If the common law is to retain its legitimacy it must remain capable of development. It must recognise the great advances made in medical knowledge and skills. It must recognise also the medical uncertainties which still exist. The law must strive to achieve a result which is fair to both parties in present-day conditions. The common law's ability to develop in this way is its proudest boast. But the present state of the law on this aspect of medical negligence, far from meeting present-day requirements of fairness, generates continuing instinctive judicial unease, exemplified in this country post-Hotson by Latham LJ's dissenting judgment in the present case, and observations of Andrew Smith J in Smith v National Health Service Litigation  Lloyd's Med Rep 90 and the Court of Appeal in Coudert Brothers v Normans Bay Ltd (27 February 2004, unreported). In the latter case Waller LJ and Carnwath LJ expressed 'disquiet' at the Court of Appeal decision in the present case. Laws LJ said he was 'driven to an unhappy sense that the common law has lost its way': paragraphs 32, 66-68 and 69.
46. The reason for this disquiet is not far to seek. The present state of the law is crude to an extent bordering on arbitrariness. It means that a patient with a 60% chance of recovery reduced to a 40% prospect by medical negligence can obtain compensation. But he can obtain nothing if his prospects were reduced from 40% to nil. This is rough justice indeed. By way of contrast, the approach set out above meets the perceived need for an appropriate remedy in both these situations and does no more than reflect fairly and rationally the loss suffered by a patient in these situations.
47. In the Court of Appeal Mance LJ, 'not without hesitation', concluded that the considerations in favour of an approach based on probabilities outweigh the contrary argument. To adopt the 'loss of chance' approach in the present, very common category of medical negligence would open a considerable gate to claims based on percentages and create a new category of case difficult to distinguish in practice from the other common cases of medical negligence. Simon Brown LJ agreed with the reasoning and conclusion of Mance LJ.
48. I am unable to agree. 'Floodgates' is not a convincing reason for letting injustice stand unremedied. This reason is invariably advanced whenever a development of the law is under consideration.
49. As to the fear of uncertainty, this arises because the difference between the Hotson type of case and the 'Gregg' type of case is one of degree. The 'diminution in prospects' approach is to be applied only when the patient's prospects of recovery, had there been no negligence, are fraught with a significant degree of medical uncertainty. This, it is said, is an imprecise boundary.
50. This objection lacks practical substance. Differences, like opposite ends of a spectrum, can be real even though one shades imperceptibly into the other. Courts are well able to determine whether a particular case falls into one category or the other. Moreover, any uncertainty caused by the need to draw this distinction is a small price to pay for avoiding the injustice produced by applying the all-or-nothing balance of probability approach across the board in all cases of medical negligence.
51. Nor does the 'diminution in prospects' approach open the door to claims based simply on negligent exposure to noxious substances which carry a risk of the development of disease in years to come. That was the problem examined in Fairchild v Glenhaven Funeral Services Ltd  1 AC 32. The 'diminution in prospects' approach set out above is confined to medical negligence cases where the claimant was already suffering from illness or injury at the time of the negligence and the defendant's duty related to the amelioration of that very illness or injury. Application of the 'diminution in prospects' approach in this type of case does not impinge upon the Fairchild decision.
52. The respondent put forward increased cost to the national health service as a practical reason why, as a matter of legal policy, the 'diminution in prospects' approach should not be adopted. Cost, it was said, will increase. More cases will be brought, and these will give rise to dispute where currently there is forensic consensus, for instance, where experts agree a claimant's chances of recovery were less than 50-50 but cannot agree on the extent to which this was so. The whole question should be left for consideration by Parliament.
53. This is a formidable submission but it is not acceptable. Whether fears of a substantially increased financial burden on the national health service are well-founded is a matter for speculation. But these fears should not be exaggerated. A damages award reflecting diminution in a patient's prospects should be made only where, in a particular case, the patient had a reasonable prospect of recovery and the diminution was a significant one; for example, if a reasonable prospect such as a 1 in 3 or a 1 in 4 chance was eliminated or, as in the present case, a 45% chance was halved. The amounts awarded should reflect the uncertainties involved, and courts should beware of giving percentage chances a spurious degree of precision.
54. More fundamentally, if a claim is well-founded in law as a matter of principle, as I believe claims of this nature are, the duty of the courts is to recognise and give effect to the claim. If the government considers that some or all of the adverse consequences of medical negligence should be borne by patients themselves, no doubt it will consider introducing appropriate legislation in Parliament.
55. Nor can I accept a further submission to the effect that the approach set out above will encourage wasteful defensive practices. Doctors, it was said, will become aware they may be sued whenever their negligence significantly diminishes a patient's prospects, whereas at present liability can arise only if the patient's pre-existing recovery prospects exceeded 50%. Accordingly, so the argument runs, doctors will be encouraged to conduct tests or make referrals in circumstances where at present they would not do so.
56. This argument is not impressive. Every doctor is fully aware he may be sued if he is negligent. There is no reason to believe that adopting the approach set out above will affect the practices followed by doctors.
57. An alternative submission advanced on behalf of Mr Gregg should be noted briefly. In the present case the trial judge found that, treated promptly, the initial spread of the cancer and the enlargement of the tumour would probably not have occurred. This, it was said, was physical injury established on balance of probability. This constituted actionable damage. The consequences flowing from this damage should be assessed in terms of diminution of prospects: what were the chances that without this spread of the cancer the subsequent adverse results would not have occurred?
58. This submission is superficially attractive. It would enable compensation to be awarded in the present case while retaining the need to prove physical damage on the balance of probability. But this solution would not get to the heart of the problem. It does not provide an answer to the fundamental issue raised at the outset of this speech.
59. I would therefore allow this appeal.
60. Had a majority of your Lordships shared this view the case would have been remitted to the Queen's Bench Division for damages to be assessed. In that event some general guidance would have been required on the assessment of damages in this type of case. That guidance will not now be needed. I add only this. The detailed facts and statistical evidence in the present case are complex. This complexity is irrelevant on the point of fundamental principle discussed above. The difficulties arising from this complexity are not created or increased by the need to make a percentage calculation when assessing damages on the loss of chance basis. The same difficulties would have existed if the judge had found that, given prompt treatment, on balance of probability Mr Gregg's condition would not have deteriorated as it did.
61. This is an action against a doctor for negligence in failing to recognise that his patient might have cancer. When Mr Gregg showed Dr Scott a lump under his arm, the doctor told him it was a collection of fatty tissues. That was the most likely explanation but unfortunately it was wrong. Mr Gregg had cancer of a lymph gland. This was discovered a year later, when another GP referred him to a hospital for examination. By that time, the tumour had spread into his chest. He suffered a good deal of pain and had to undergo a particularly debilitating course of high-dose chemotherapy. The treatment temporarily destroyed the tumour but was followed by a relapse which left Mr Gregg with a poor prospect of survival.
62. Mr Gregg alleged in his particulars of claim that Dr Scott ought to have referred him to a hospital for examination. His "particulars of pain and injury" alleged that if he had been diagnosed earlier "there would have been a very high likelihood of cure". I shall come back in a moment to what, in this context, was meant by a cure. In the event, he said, the prospects of obtaining a cure had been reduced to below 50%.
The judge's findings
63. The judge found that Dr Scott had been negligent in excluding the possibility that the growth might not be benign. A routine reference to a hospital would have settled the matter. There has been no challenge to this finding.
64. The question which has given rise to this appeal is whether Dr Scott's negligence caused injury to Mr Gregg. As I have said, the injury of which he complained was that the delay had reduced his prospect of a cure to less than 50%. The expert witnesses treated a cure as meaning survival for more than 10 years. They produced statistical evidence about the progress of the disease in other patients. The judge summarised the effect of this evidence by finding that if Mr Gregg had been treated earlier, the cancer would probably not have spread as quickly as it did. The treatment would probably have produced a remission. But a remission might have been followed by a relapse and the probability was that someone with Mr Gregg's condition would either not have responded to treatment or, if he did respond, would afterwards have relapsed. In statistical terms, the evidence showed that, out of 100 patients suffering from a similar condition, only 42 would, even if treated immediately, survive more than ten years. The rest would have died earlier, either because they were part of the minority which did not respond to treatment or because, having responded, they then relapsed. What the delay had done, according to the experts, was to reduce the chances of survival for more than 10 years even further, from 42% to 25%.
65. On this evidence the judge held that the delay had not deprived Mr Gregg of the prospect of a cure because he would probably not have been cured anyway. He therefore dismissed the action.
The Court of Appeal
66. In the Court of Appeal Mr Gregg's counsel advanced two arguments. The first was that Mr Gregg had proved that the delay had caused him injury because the judge found that if he had been treated earlier, the cancer would probably not have spread as quickly as it did. He was entitled to compensation for this injury and that should include the reduction in his chances of survival. The second argument was that quite apart from any other injury, the reduction in his chances of survival was itself a compensatable head of damage. The first argument was accepted by Latham LJ but the majority of the Court (Simon Brown and Mance LJJ) rejected both and dismissed the appeal. These two arguments were again deployed in the argument before your Lordships' House.
The quantification argument
67. The first argument is based upon the well-established principle that in quantifying the loss likely to have been caused by the defendant's wrongful act, the court will take into account possibilities, even though they do not amount to probabilities: Mallett v McMonagle  AC 166, 176. A common example is the possibility that a claimant who has been injured by the defendant will suffer some complication such as arthritis in a damaged joint. This principle applies when the extent of the loss depends upon what will happen after the trial or upon what might hypothetically have happened (either before or after the trial) if the claimant had not been injured: see Doyle v Wallace  PIQR Q146, in which the loss of earnings caused by the injury would have been greater if the claimant had qualified as a drama teacher.
68. This principle has in my opinion no application to the present case because it applies only to damage which it is proved will be attributable to the defendant's wrongful act. Thus in Doyle v Wallace there was no dispute that if the claimant had qualified as a drama teacher, the loss of the additional earnings would have been attributable to the injury which the defendant had caused her. Likewise, if the injured joint develops arthritis, there is usually no dispute that the arthritis will be attributable to the injury. In the present case, the question was not whether Mr Gregg was likely to survive more than 10 years (the finding was that he was not) but whether his likely premature death would be attributable to the wrongful act of the defendant.
69. The distinction between the question of whether damage is attributable to the defendant and the quantification of damage proved to be so attributable was succinctly made by a Canadian judge (Master J in Kranz v M'Cutcheon (1920) 18 Ontario WN 395) quoted by Lord Guthrie in Kenyon v Bell 1953 SC 125, 128:
70. Latham LJ, who accepted the quantification argument, put the matter in this way (paragraph 41):
71. I respectfully think that this formulation begs more than one question. It is true that the delay caused an early spread of the cancer and that this reduced his percentage chance of survival for more than 10 years. But to say that the claimant can therefore obtain damages for the reduction in his chances of survival assumes in his favour that a reduction in the chance of survival is a recoverable head of damage; an issue raised by the claimant's second argument which Latham LJ said (at paragraph 41) that he did not need to decide. On the other hand, if the claim is for actually depriving him of survival for more than 10 years, the question is whether the spread of the cancer caused it. The judge's finding was that it did not. It was likely that his life would have been shortened to less than 10 years anyway.
Loss of a chance
72. The alternative submission was that reduction in the prospect of a favourable outcome ("loss of a chance") should be a recoverable head of damage. There are certainly cases in which it is. Chaplin v Hicks  2 KB 786 is a well known example. The question is whether the principle of that case can apply to a case of clinical negligence such as this.
73. The answer can be derived from three cases in the House of Lords: Hotson v East Berkshire Area Health Authority  AC 750, Wilsher v Essex Area Health Authority  AC 1074 and Fairchild v Glenhaven Funeral Services Ltd  1 AC 32.
74. In Hotson the claimant was a boy who broke his hip when he fell out of a tree. The hospital negligently failed to diagnose the fracture for five days. The hip joint was irreparably damaged by the loss of blood supply to its cartilage. The judge found that the rupture of the blood vessels caused by the fall had probably made the damage inevitable but there was a 25% chance that enough had remained intact to save the joint if the fracture had been diagnosed at the time. He and the Court of Appeal awarded the claimant damages for loss of the 25% chance of a favourable outcome.
75. The House of Lords unanimously reversed this decision. They said that the claimant had not lost a chance because, on the finding of fact, nothing could have been done to save the joint. The outcome had been determined by what happened when he fell out of the tree. Either he had enough surviving blood vessels or he did not. That question had to be decided on a balance of probability and had been decided adversely to the claimant.
76. In Wilsher a junior doctor in a special care baby unit negligently put a catheter in the wrong place so that a monitor failed to register that a premature baby was receiving too much oxygen. The baby suffered rentrolental fibroplasia ("RLF"), a condition of the eyes which resulted in blindness. The excessive oxygen was a possible cause of the condition and had increased the chances that it would develop but there were other possible causes: statistics showed a correlation between RLF and various conditions present in the Wilsher baby. But the causal mechanism linking them to RLF was unknown.
77. The Court of Appeal awarded damages for the reduction in the chance of a favourable outcome. Again this was reversed by the House of Lords. The baby's RLF was caused by lack of oxygen or by something else or a combination of causes. The defendant was liable only if the lack of oxygen caused or substantially contributed to the injury. That had to be proved on a balance of probability.