1 THE COURT: The appellant's mother was badly hurt in a motor accident on 27 June 1982 when she was pregnant with him. He was conceived in January 1982 and born on 6 October 1982 with cerebral palsy.
2 The accident happened when a vehicle driven by an intoxicated man travelled through at a stop sign at an intersection, at about 60 kilometres per hour, and struck the driver's side of a vehicle driven by the appellant's mother. Her mother, who was a passenger in that vehicle, and the driver of the other vehicle were killed. The appellant's elder brother, the other passenger, who had been born in 1981, was also badly hurt. He suffered a fractured skull.
3 The appellant's mother suffered a fracture of the left temporal region, brain damage, a lesion to her left optic nerve, two fractured thoracic vertebrae, six fractured ribs, ante-partum haemorrhage with a risk of premature birth of the appellant, and abrasions, lacerations and soft tissue injuries to her head, neck, back, arms and legs. She was initially taken by ambulance to Canterbury Hospital. Later on the same day, she was transferred to Royal Prince Alfred Hospital. A few days later she was transferred to King George V Hospital, from which she was discharged on 6 July 1982. Because of further ante-partum haemorrhaging, she was readmitted to hospital from 9 August to 1 October and again on 3 October 1982. She was still in hospital on 6 October when another haemorrhage led to a decision to deliver the appellant by caesarean section, which was carried out on that day.
4 Some months after the appellant was born on 6 October 1982, he was diagnosed as suffering from cerebral palsy. It is common ground in the case that his cerebral palsy results from hypoxic ischaemia or perfusion failure, Hypoxic ischaemia and perfusion failure are technically different, but the difference is not important in this case. Both involve the disruption of blood supply to the brain, which leads to a deprivation of oxygen. For the sake of brevity we will call them perfusion failure. while he was in his mother's womb. That is, the appellant was wholly deprived of the blood supply providing oxygen to his brain for about 10 minutes or partially deprived of blood, with depleted oxygen, for about 20-30 minutes, causing a destructive lesion on his brain.
5 It is not in dispute that the respondent is liable for the appellant's damages if the collision probably caused his cerebral palsy. However, the trial judge held that that had not been proved. By this appeal, the appellant challenges that conclusion, and seeks an order that the action be remitted to the Common Law Division to assess his damages.
6 Although it will later be necessary to refer to some matters of detail, it is unnecessary to discuss each of the appellant's 59 grounds to dispose of this appeal. Nor do we consider it necessary, or even desirable, to record or summarise, analyse and discuss all the evidence of the expert witnesses and the arguments which the parties advanced in relation to their respective expertise and opinions. Ten experts gave oral evidence; four paediatric neurologists, a paediatric neurosurgeon, two neuroradiologists, an obstetrician, a rehabilitation specialist, and a general practitioner. Written reports from ten other medical practitioners were tendered in evidence. Several of the experts For example, Professors Zimmerman, Stephenson, Ouvrier and Evrard. commented on the interdependent nature of their specialist fields. Detailed discussion of the numerous matters debated and the diversity of the opinions expressed creates a major risk of intermediate issues diverting attention from the ultimate question of probable causation.
7 Difficult conceptual issues which are sometimes associated with causation do not arise in this case. There were only two possible causes of the perfusion failure which caused the appellant's cerebral palsy. The injuries to his mother in the motor vehicle collision undoubtedly could have caused hypoxic ischaemia or perfusion failure to the foetus then in her womb. The only alternative is that the perfusion failure had a completely unknown cause, apparently an unnoticed (and presumably minor) event subsequent to the collision but unrelated to it. Less than 1 case of cerebral palsy in 200 is caused by perfusion failure which has an unknown cause.
8 The trial judge provided a helpful description of the basic anatomy and foetal development of the brain in the following passage:
"The basic anatomy of the brain includes (working outwards from the inner brain) the ventricles (the space containing cerebra-spinal fluid), the white matter (being the bulk of the brain), then a thin layer of grey matter (the cortex). Cells in the cortex are "wired" together in the white matter, so that damage to the white matter impairs functions located in the cortex, including intellectual and motor functions.
In the development of the foetus, cells migrate from a position adjacent to the ventricles, through the white matter to the cortex, where they mature. As cells build up in the cortex, gyri (hills) and sulci (valleys) appear on the surface of the brain. Interference with the migration and/or maturation of cells on route or in the cortex during this stage of development is called a migrational disorder.
Migrational disorders include polymicrogyria which , in its relevant form, involves a flattening of the surface of the cortex and small irregularities on the flattened surface. At some stage, cells called acrocytes are formed. They generate gliosis (a type of scar tissue peculiar to the brain) following injury.
… … …
Porencephaly is a pathological loss of white matter. Technically speaking, it occurs early in the development of the foetus, but the expression is used loosely to cover such loss at a later stage also. The area of loss is called the porus. The porus is filled by cerebrospinal fluid and takes the form of an enlarged ventricle.
Periventricular leucomalacia is the technical term for a loss of white matter later in foetal development.
…"
9 The trial judge's conclusion that the appellant had not proved that his cerebral palsy was probably caused by the injuries which his mother suffered in the collision was wholly dependent on his finding that, at that time, she was in the second trimester of her pregnancy. It was common ground that, conventionally, the second trimester extended from the 14th to the 26th week after conception. Based on his mother's not completely certain recollection that her last menstrual period prior to the appellant's conception commenced on 12 January 1982 and evidence that conception usually occurs about a fortnight after the commencement of a menstrual period, it was estimated that the collision was about 23 weeks and the birth about 37 weeks after conception. While there was evidence which cast doubt upon the reliability of the periods of 23 and 37 weeks (i) The appellant's mother's evidence was that she did not have a menstrual period while breastfeeding his elder brother between June 1981 and "December, early January" but "suddenly [on a date about which she 'wasn't a hundred per cent certain'] got a period after stopping to breast-feed...".
(ii) The appellant was very heavy when born, with an Apgar score of 8 and then 9. He was described as like a "full term" baby., if the question whether the appellant's mother's pregnancy was in the second or third trimester when she was injured is considered in isolation, the trial judge's conclusion that the pregnancy was in the second trimester was open on the evidence. Even so, on that hypothesis, when the appellant's mother was injured, her pregnancy was near the end of the second trimester and the beginning of the third trimester.
10 The trial judge's decision that causation was not proved also depended on a sharp distinction which his Honour drew between the respective indicia and consequences of perfusion failure in the second and the third trimesters of pregnancy. On that basis, the trial judge concluded that the perfusion failure which caused the appellant's cerebral palsy occurred in the third trimester of his mother's pregnancy. Again, if that issue is considered in isolation, there was an evidentiary basis for his Honour's conclusion, although the appellant argued that his Honour's assessment of expert evidence related to this matter involved error.
11 The principal factor which led the trial judge to find that the perfusion failure occurred in the third trimester was that Magnetic Resonance Imaging of the appellant's brain disclosed extensive gliosis and his Honour held, on the basis of evidence from some of the expert witnesses, that "[s]uch gliosis is not seen on [Magnetic Resonance Imaging] in cases of second trimester injury". Taken literally, that categorical statement is inconsistent with the formation of gliosis from an injury on even the last day of the second trimester notwithstanding that an injury not long afterwards could produce gliosis.
12 His Honour also expressly rejected "… the theory that gliosis may form later in a response to a second trimester injury".
13 The trial judge said that three further matters fortified his conclusion that the perfusion failure which caused the appellant's cerebral palsy did not occur in the second trimester of his mother's pregnancy, even at the end of that trimester, but occurred in the third trimester, even if early in that trimester, although his Honour considered these further matters "… [did] not … have the same conclusive force as the presence of gliosis". The further matters were:
(i) Magnetic Resonance Imaging of the appellant's brain did not disclose polymicrogyria or any cognate migrational disorder, which, "… if this were a second trimester lesion, one would expert to find evidence of …".
(ii) "… if a severe lesion of the kind seen in this case had occurred in the second trimester, it would be likely to cause microcephaly. There is no microcephaly in this case"
(iii) No sign of ventricular enlargement was evident on ultrasound examination in August and September 1982, contrary to what would be expected "… if the lesion occurred at or shortly after the time of the [collision] in July 1982 …".
14 Inevitably, his Honour's findings that the collision which caused the appellant's mother's injuries occurred in the second trimester of her pregnancy and that the perfusion failure which caused the appellant's cerebral palsy occurred in the third trimester led to his decision that the appellant had not proved that the collision caused the cerebral palsy.
15 Despite its logical appearance, we consider that the trial judge's reasoning process was flawed. The separate determination of the trimester of the appellant's mother's pregnancy in which her injuries occurred and the trimester in which the appellant experienced perfusion failure, and the treatment of those findings as established beyond question, caused potentially material matters to be overlooked or given insufficient weight, and distracted attention from the ultimate choice between the two possible causes of the appellant's cerebral palsy which his Honour had to make by reference to the whole of the circumstances.
16 In our opinion, the approach of the trial judge is susceptible to a number of criticisms. For example, the sharp distinction drawn between events occurring in the second trimester of pregnancy and events occurring in the third trimester and associated indicia and consequences imports a degree of precision which is unrealistic and incompatible with the overall tenor of the expert evidence, especially when regard is had to the uncertainty concerning the date of the appellant's conception and the variability between individuals in length of "normal" pregnancy, rates of foetal development and the production of gliosis.
17 The approach adopted by the trial judge also had the consequence that, since attention was primarily concentrated on the trimester or trimesters in which the collision and the perfusion failure occurred, factors which might otherwise have influenced the decision on the ultimate issue had to be explained away, if necessary by reference to such considerations as the demeanour of expert witnesses. The problems concerning a trial judge's preference for some expert opinions over others, the legitimacy of his or her use of the demeanour of witnesses in forming such views, and the deference which this Court should pay to findings made at trial are frequently discussed. See, for example, Fleming v R (1998) 158 ALR 379; State Rail Authority of NSW v Earthline Constructions Pty Ltd (In liquidation) (1999) 73 ALJR 306; Jsekarb Pty Ltd v Plane (Unreported NSWCA, 23 December 1998). See also the "Postscript to evidence notes" in (1998) 72 ALJ at pp 333-334. While it is theoretically possible for a clash of expert views to be resolved by an assessment of credibility, that is not a very satisfactory approach in this case. There was a substantial measure of agreement between the expert witnesses on some issues, and most of the experts acknowledged that many, if not all, of the issues on which there was disagreement are difficult and scientifically unsettled, with recognised experts legitimately holding different views based on their respective knowledge and experience. Findings by a lay tribunal of fact with respect to such controversial matters which are based on appearances or mannerisms or other aspects of demeanour are necessarily arbitrary, and an unsatisfactory foundation for a conclusion that an unknown event which is only a slight possibility is a more probable cause of an injury than a specific event which is known to be capable of causing such an injury.
18 Further, there is a degree of circuity involved in the trial judge's basic approach. For example, in the circumstances here, where there is an element of doubt about the date of conception and hence the number of weeks since conception when the accident happened, indications that perfusion failure probably occurred in the third trimester ought not be regarded as necessarily excluding the accident, the one known event capable of causing that failure, from consideration as the event that in fact caused it; on the contrary, those indications should lead to the consideration of other questions: these would include whether that one known event probably occurred at the beginning of the third trimester, and the allied question, whether the conventional trimester lengths applied precisely to Mrs Papadopoulos: these questions would not involve a circular approach.
19 As a result of the approach adopted, a number of factors which were inconsistent with the trial judge's views of the trimester in which (i) the collision and (ii) the perfusion failure occurred, were given scant significance by his Honour in reaching his final conclusion. Thus, for example, the labour contractions which the appellant's mother experienced from about five hours following the collision were held by the trial judge to indicate "… no more than that [the collision] initiated the contractions …", not "… that the foetus was likely to have been traumatised".
20 Similarly, his Honour held that the appellant's mother's vaginal bleeding post-accident, which finally led to the appellant being delivered by caesarean section, indicated "… a disturbance of the uterus and its contents", but not "[d]amage to the foetus …".
21 His Honour also said "I do not find that Mrs Papadopoulos was rendered unconscious at any stage. Whether she was rendered unconscious at the time of the accident and had recovered consciousness by the time she was admitted to the Canterbury Hospital I do not know". We do not consider this open finding satisfactory. There was a body of evidence on the topic, and a finding that the collision caused the appellant's mother to lose consciousness would have added another matter tending to the likelihood that his mother's injuries were the cause of the appellant's perfusion failure, especially when considered in connection with his mother's contemporaneous ante-partum haemorrhage. The blood pressure within the circulatory system of a foetus is responsive to the mother's blood pressure, which, if it drops, can reduce the blood flow, and hence oxygen, transmitted to the foetus' brain. Shock can produce a reduction in blood pressure, which is also lowered if a person is rendered unconscious. His Honour's statement that he did not "know" whether Mrs Papadopoulos had become unconscious at the time of the accident followed closely on what he had said in the previous paragraph that "There is no secure evidence that Mrs Papadopoulos was rendered unconscious at any stage". The word "secure" is troubling. The question was whether on the balance of probabilities it was more likely than not that the force of the collision knocked Mrs Papadopoulos unconscious.
22 When regard is had to the suddenness and force of the collision, the injuries to the passengers in the car driven by Mrs Papadopoulos (the death of her mother, a fractured skull among other injuries, to her son) and the severity of Mrs Papadopoulos's own injuries, which included serious head injuries A letter dated 10 June 1983 from Royal Prince Alfred Hospital, where Mrs Papadopoulos was admitted about four hours after the accident, said she had a fracture of the left temporal region. (It also said that ultrasound examination "confirmed a twenty-four to twenty-four-and-a-half week pregnancy". The judge said that only one item in the letter (not either of those just mentioned), was controversial.), an inference that she became unconscious is readily available. At Canterbury Hospital it was noted that she was still "badly confused [and] … disorientated in time and place" on the following day. Indeed, she suffered from post-traumatic amnesia for three days after the collision. The neurosurgeon who attended her at Canterbury Hospital (where she was taken before being moved to Royal Prince Alfred Hospital) stated in a letter dated 10 December 1982 that she "was brought in unconscious", no doubt some time after the collision since the ambulance officers had also had to deal with her passengers and the dead driver of the other car, although other hospital records said that she was "conscious … since admission". The latter statement is insufficient to prevent a finding that it is probable that the appellant's mother was unconscious for a period after the accident, although she regained consciousness on, or shortly after, her arrival at Canterbury Hospital. There is another reference to loss of consciousness in the accident in a letter dated 3 December 1982. (In December 1982 there was not yet any suspicion that the plaintiff might be suffering from cerebral palsy.) This is a finding we make, on the civil standard of proof.
23 After the appellant's mother arrived at Royal Prince Alfred Hospital at approximately 7.40pm on the day of the collision she was examined in the Emergency Department by the Neurosurgical Registrar and the Obstetrics and Gynaecological Registrar and transferred to the Intensive Care Unit. In the letter from the hospital already referred to in n.3 it was said: "She was noted to have a low haemoglobin According to the Australian Concise Oxford Dictionary, haemoglobin is a "red oxygen- carrying substance containing iron, present in the red-blood-cells …". and this was thought secondary to her injuries and thalassemia". Thalassemia is a blood disease which produces fluctuations in haemoglobin level and hence in oxygen supply. A haematology consultant who examined the appellant on 5 July 1982 considered that her injuries, which had resulted in the loss of 1.5 pints of blood, had caused a sudden fall in haemoglobin since the collision.
24 Earlier, it was noted that the trial judge considered that the results of ultrasound examinations in August and September 1982 fortified his conclusion that the appellant had not proved causation. The appellant's mother had ultrasound examinations on a number of occasions both prior to and after the collision. The last antenatal ultrasound examination was conducted on 27 September 1982, little more than a week prior to the appellant's birth on 6 October 1982. No abnormality was detected at any time prior to, or at, his birth. Little, if any, weight was given to this circumstance as a matter which reduced the possibility that there was some antenatal event, other than his mother's injuries in the accident, which probably caused the appellant's perfusion failure cerebral palsy.
25 We do not propose to canvass all the potentially material factors. We think it necessary however to say something further about the judge's reasons for expressing concern about "the reliability (and in two instances the credibility) of certain of the appellant's expert witnesses" by which he seems to be referring to Professors Stephenson, Ouvrier and Evrard, on the grounds that he did.
26 In the case of Professor Ouvrier for example, his Honour noted that in a report dated 20 June 1983, the Professor had said he had "a strong suspicion that the infant's condition actually is related to damage suffered in the accident", and in a later report dated 27 June 1992 had said "On the balance of probabilities, I believe that the motor vehicle accident which occurred on 27th June 1982 was the cause of this child's cerebral palsy".
27 The judge regarded the change in expression as a "shift" which he found "disquieting". It seems to us to have an obvious explanation which does not go to the discredit of Professor Ouvrier. The first report uses the language of a medical man, trained in scientific method, and not accustomed to think in, or approve of, the bare balance of probabilities approach of common lawyers. We think that the personal opinion lying behind the earlier report was that Professor Ouvrier thought there probably was a link between the accident and the cerebral palsy, but that it could not be established in terms of scientific method. So, using the language of his own discipline, he expressed himself in terms of "strong suspicion". For a person using the vocabulary of scientific method, "strong suspicion" is in itself a strong statement. What then happened in the second report, in our view, was that he expressed the same opinion he had earlier held, but this time in the legal language which experts are pressed by lawyers to use in cases like these, and which is quite permissible in regard to legal questions asking whether something is more probable than not.
28 The trial judge further referred to a third report by Professor Ouvrier dated 9 August 1993 which he thought showed a further "progression". We think the explanation for the language used is the same as in regard to the second report. To us, the third report, like the second, seems to show Professor Ouvrier expressing the same opinion he held all along.
29 Another example of what seems to us to be questionable fact finding on the part of the judge which at least partly contributed to his over-critical findings about Professor Ouvrier was his view about Mrs Papadopoulos's abdominal pain reported in the letter of 10 June 1983 from Royal Prince Alfred Hospital earlier referred to. The trial judge thought this reference was likely to be a mistake, because no other records mentioned it. The judge however had noted that it had not been possible for all the records to be put before him. We think it unlikely that the detail was invented. It seems to us more likely than not to have been taken from some contemporary record (of 1982) no longer available at the time of trial (in 1995). Some of the trial judge's criticism of Professor Ouvrier was based on his use of this fact which his Honour was not prepared to accept. Restore the fact, and Professor Ouvrier's opinion should, on the trial judge's premises, regain some weight.
30 We think the trial judge's evaluation of Professor Evrard was also questionable. We will confine ourselves to one example. This occurs in the trial judge's discussion of different possible ways mentioned by Professor Evrard in which the car accident might have contributed to the appellant's cerebral palsy. The passage says:
"Professor Evrard now preferred to find a relationship between the MV and the cerebral palsy based on what he called 'commonsense'. He said that the chance of a coincidence between the fact of the MVA and the plaintiff being born with cerebral palsy was so small statistically that there was a very low probability that the relationship was merely coincidental.
The argument went this way. Cerebral palsy caused by perfusion failure was a rare condition. Injury to a pregnant woman in a MVA was not a commonplace occurrence either. The probability that the sequence of events might occur by pure chance was therefore extremely low. Therefore, the two events were likely to be related.
I do not know where to begin in responding to this approach. Cerebral palsy of this type, like any other rare event, will always occur after other events have occurred, some of which will be rare. Why one would relate the condition to a particular prior event because the condition is rare, I do not know. Why one would relate it to a particular prior event because that event is rare, I do not know. Why do so because both the condition and the particular prior event are rare, I do not know."
31 What the trial judge does not mention here is the fact, much stressed in the case, that no other explanation was put forward by the respondent for the appellant's cerebral palsy In his re-examination, Professor Zimmerman appeared to raise the possibility that the appellant's mother's bleeding shortly before the appellant was delivered by caesarean section might have caused hypoxic ischaemia. The trial judge expressly rejected the appellant's mother's episodes of bleeding as a cause of the appellant's hypoxic ischaemia or perfusion failure, which he attributed to an unknown event. It seems highly likely that the bleeding which occurred between the collision and birth was connected to the collision.. If that fact be understood as part of the background to Professor Evrard's reasoning, then his reasoning does not seem to us to have deserved to be criticised in the way it was.
32 After reading Professor Evrard's curriculum vitae, his written material and his evidence (given by videolink in good but not perfect English) and considering the trial judge's criticisms of it, we do not think his opinions should have been put on one side in the way they were. We do not say the trial judge was bound to accept them, but that he should have given some weight to the fact that a world expert in the field was prepared to express the "commonsense" opinion that he did. We do not agree that Professor Evrard's motivation for his expression of his commonsense opinion was that suggested by the judge. The impression we have of his evidence is that of an expert seeking to discuss the possibilities relevant to the appellant's palsy, without any particular bias to the appellant's case, but wanting to support his opinion, genuinely held, that the car accident was more probably than not a contributing cause of the appellant's brain defect.
33 The other matter we wish to mention is a general consideration widely known to the community, and of which evidence was given. Severe shaking can produce brain damage in a baby in its first year of independent life and the brain of a foetus is smaller, softer and more prone to injury. The appellant's mother's injuries starkly reveal the violence to which she, and the foetus in her womb, were subjected.
34 In our opinion, unnecessary findings on intermediate factual issues distracted the trial judge from the ultimate question of causation, which depends upon the proper inference to be drawn from all material circumstances and is not, in this case as in many others, "susceptible of scientific demonstration or proof". cf Malec v J C Hutton Pty Ltd (1990) 169 CLR 638, 643. A consideration of all the circumstances, including the expert opinions which favour the trial judge's conclusion, leads us to the conclusion, not as a matter of science, but on the non-scientific, legal test, the balance of probabilities, that the appellant's cerebral palsy was contributed to by the collision in which his mother was injured. We think the statistical improbability of an unexplained cause combined with the actuality of the injuries to the appellant's mother is a sound support for such a conclusion.
35 We would allow the appeal, set aside the judgment below, and enter judgment in favour of the appellant for damages to be assessed, the respondent to pay the costs of the trial and of the appeal.