Allan D Spigelman and Peter Dwyer. Is there a link between work-related stress and colorectal cancer? Med J Aust 2004; 180 (7): 339-340. [Medicine and the Law] <http://www.mja.com.au/public/issues/180_07_050404/spi10205_fm.html>|
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Gordon Samuels
MJA 1998; 168: 84-87
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Introduction -
Matters of opinion -
The role of the expert -
Expert qualifications -
From adversaries to truth... -
Science v Law -
Expert error -
Judging the experts -
References -
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©MJA1998
Introduction |
When Dr Julian Lee wrote inviting me to give the 1997 AMA (NSW) Oration,
he suggested that I might care to address the relationship "between
our two professions and its current implications". Plainly, one of
the two professions to which he referred was that of medicine. The
other could scarcely have been the profession of Governor, which, so
far as I am aware, lacks the formal structure, the need to have survived
rigorous inquiry into some intellectual qualification and the right
of self-regulation which normally denote a profession. So I
concluded that he was referring to the profession which I pursued in a
former incarnation when I was, as most of you will know, a barrister
and, later, a judge.
As a lawyer in both of those roles I enjoyed close professional relationships with the medical profession. As a barrister I was retained by a medical insurer and did my best to act as shield and buckler for those doctors -- in those days a small number -- who had the misfortune to find themselves in the courts as defendants. I often relied on the expert evidence of medical practitioners, and on different occasions did my best to destroy the testimony of others. As a judge I sat on varied cases involving doctors in one capacity or another, and throughout the time I much enjoyed the intellectual comradeship presented by the Medico Legal Society of New South Wales and the Australian Academy of Forensic Sciences. It seemed to me, however, that what Dr Lee had in mind was the professional relationship which exists between the medical and the legal professions, and which links them as the leading participants in the litigious process in the courts. It is to that aspect which I propose to direct my remarks tonight. Despite changes in the procedure for recovering damages for injury sustained on the roads and in the workplace, such actions remain regular fixtures in the common law lists. It follows that doctors are still the expert witnesses who are most in demand, and their evidence is the scientific testimony most commonly presented to the courts. I propose to say a word or two about expert witnesses and their evidence, with particular reference to medical witnesses, and to describe shortly the way in which our current forensic procedure prescribes how that evidence is to be given and its cogency tested. Then I will say something about the problem which exercises -- I might say, in some cases, agitates -- both doctors and lawyers of ensuring that expert testimony is of a standard which the court may accept and act upon. There has been a recent decision of the Supreme Court of the United States,1 which, although not directly of authority in Australia, may well produce a substantial effect upon the way in which Australian courts in the future assess and admit scientific evidence, including, of course, evidence concerning medical science. |
Matters of opinion |
Expert witnesses have not always enjoyed a good reputation. They have
tended to present the same image in legal literature as the lawyer does
in Shakespeare: venal, grasping and fit to be hanged. The following
acrid passage is a fair sample: "These witnesses are usually required
to speak, not to facts, but to opinions; and when this is the case, it is
often quite surprising to see with what facility, and to what extent,
their views can be made to correspond with the wishes or the interests
of the parties who call them." That observation comes from the
celebrated text book Taylor on evidence, but there are
judicial comments to the same effect, referring, for example, to the
"kind of unconscious bias which is a well known characteristic of
expert evidence".2 However,
judicial comment has also included pleasing accolades, such as those
bestowed in a case in New South Wales upon medical witnesses who were
demonstrating with singular tenacity the philosophical dichotomy
between physician and surgeon.3
The physicians who gave evidence preferred proof by
scientific means; the surgeons by experience and observation.
Some of the criticism made of the expert witness may be justified. But, in all fairness, it should be shared with the lawyers, who have cast expert witnesses in a particular role which they often find uncomfortable and restricting. It was the lawyers who originally altered the expert's function from that of assessor to that of witness. The allegation of undue adherence to the client's cause is made by those who have created, and who perpetuate, the forensic techniques to which the expert has been forced to adapt. It is not the expert's own choice to be a partisan, but a consequence of the pressures and temptations exerted by the adversarial system in which he or she has to play a part. |
The role of the expert |
The function of expert witnesses is to inform the tribunal, judge or
jury, of matters about which its lack of specialist skill or
experience would leave it ignorant. It is intended to substitute
knowledge for speculation. The duty of the expert has been defined in
this way: "...to furnish the judge or jury with the necessary
scientific criteria for testing the accuracy of their conclusions so
as to enable the judge or jury to form their own independent judgement
by the application of these criteria to the facts proved in evidence."4
The expert's task is twofold. First, to furnish basic scientific or technical data. Second, to present inferences and conclusions from the facts which the judge or jury, for lack of specialised knowledge, cannot draw themselves. The expert is introduced to carry the proof to the conclusion for which the party presenting that evidence contends. But the limits of the role are drawn where the expert's special knowledge ceases to be significant. |
Expert qualifications |
Before the expert can perform the assigned function, he or she must be
qualified to furnish the evidence to be tendered. This question of
qualification rarely presents itself in the average case where the
evidence of doctors, engineers and accountants, let us say, is
primarily concerned. It is not the qualification to give the evidence
which has generated recent controversy, but rather the quality of the
evidence which a qualified expert offers. The High Court of Australia
has dealt in detail with the skill necessary to qualify a witness as an
expert, and with the circumstances in which the testimony of a skilled
person is admissible. The putative expert must have undertaken a
professional course of study which has given him or her more
opportunity of judging the matters in question than other people; or
must have completed the professional study of what has been described
as "an organised branch of knowledge" relevant to the subject matter
of the inquiry.5 A leading
text writer on the law of evidence has suggested that the only true
criterion is whether "on this subject can [the tribunal] from this
person receive appreciable help".6
The standard to be applied is somewhat indefinite; and from this it follows that any medical practitioner may be (and nearly always is) admitted to give evidence upon any branch of medicine. And one can always be found who will. It is unfortunately true that the law does not require the best possible witness as it requires the best possible evidence; and the safeguard is said to be the good sense of the tribunal of fact which must itself determine which of the witnesses it will accept. Up to the present, Australian law has not contained any criterion for evaluating the quality of expert evidence as a threshold element to be satisfied as a test for admission. In the average case where there is a conflict of medical evidence, the dispute is most often about a commonplace medical condition in which specialised support for any of the assertions that might be made may readily be found. In the unusual case, the most novel proposition will have its adherents, who may compensate in vehemence for what they may lack in scientific authority. There is a prime example of this situation, and of the difficulties of applying any stringent limitation upon the testimonial capacity of persons prima facie qualified. The issue in a case was whether the deceased's acute lymphatic leukaemia had resulted from trauma. The evidence of a doctor was admitted (and accepted by the jury) which answered the question affirmatively, on the footing of a scientific phenomenon known to the witness as "autonomic dyspraxia", but not at all within the professional experience of any of the eminent practitioners who gave evidence on the other side.7 |
From adversaries to truth... |
The nature of expert evidence and the way in which it is given will be
largely determined by the procedure of the court; and its effect is
greatly influenced by the capacity of the court to understand and
apply it. The basic forensic procedure which applies, with
variations, in all Australian courts is the adversarial system or
procedure. Its essence is that the parties, and not the court,
determine the issues which they will fight, and themselves select and
call the evidence in support of them. The cases are generally
conducted by advocates for the parties, and, as a general rule, the
judge's intervention is, and is intended to be, comparatively minor.
It is thus the responsibility of the parties to prepare their cases and marshal their witnesses. The court provides the formal means, backed by sanctions, by which the witnesses may, if necessary, be summoned to the trial and documents procured for inspection and tender. It is an essential consequence of the adversarial system that the parties are not obliged to call all the relevant evidence which they may have in their possession. They are entitled to call only that which favours their own case, and, with certain important exceptions, may properly not disclose that which does not. Traditionally, the adversarial trial has been regarded as a gladiatorial combat, and sporting metaphors abound. They are not always accurate, but, as Lord Devlin has observed,8 our system is a trial of strength rather than an inquiry on the European model produced by the traditions of the Roman law, in which the judge, rather than the parties, conducts and controls the proceedings as an inquisitor rather than a referee. Since our mode of trial does not involve painstaking and wide-ranging investigation conducted by an impartial inquisitor, it is not designed to ferret out the truth in any absolute sense. The judge, for example, is limited by the material which the parties choose to offer; and, in a criminal case, save in the most exceptional circumstances, is not permitted to call a witness of his or her own motion.9,10 Although the position in Australia is uncertain, there is authority for the view that in a civil action the prohibition upon the judge's calling a witness is absolute.11-14 The adversarial trial is, above all, intended to produce a winner. In our system the question is not "What is the truth of the matter?". It is not "Who killed X?". It is not even "Did the accused kill X?". It is "Has the prosecution proved beyond reasonable doubt that the accused killed X?", because the issue is whether the party carrying the burden of proof has discharged it. I think that in most cases the adversarial conflict does elicit the truth, but it cannot be regarded as designed to do so. |
Science v Law |
The procedure adopted in our courts tends to exacerbate fundamental
differences in approach between doctors and lawyers. Medicine is a
science and law is not. Developments in medicine are made by
experiment and observation; in law they are made by the decisions of
legislatures and judges. A medical fact is one which can be
empirically supported or clinically determined; a legal fact is one
which is more probable than other countervailing facts. A trial
lawyer seeks to win by tipping the scales of proof in his or her favour by
the preponderance of cogent evidence. Hence, the search is for
positive answers and firm conclusions; for the means of establishing
the proposition that will prove the issue in dispute and end the case.
Beyond that the lawyer has no commitment.
Thus, lawyers often find difficulty in dealing with the expert, whether forensic scientist or medical practitioner, who does have a continuing commitment to the search for a final answer which, nevertheless, the scientific methodology tends to deny. Karl Popper has said: "When we think we have found an approximation to the truth in the form of a scientific theory which has stood up to criticism and to tests better than its competitors, we shall, as realists, accept it as a basis for practical action, simply because we have nothing better (or nearer to the truth). But we need not accept it as true; we need not believe in it (which would mean believing in its truth)."15 Furthermore, the details of forensic procedure place restrictions sanctioned by the rules of evidence upon the scientist's, and the doctor's, accustomed method of exegesis and description. The need to deploy closely reasoned opinion by means of question and answer, and the danger of fatal disconnection if the interrogating counsel is inept or the judge's interventions unduly copious, are not designed to promote lucidity. Further, expert witnesses are irritated by the way in which cross-examining counsel is able to detach and attack certain portions of their evidence or force them into logical qualifications. An expert witness, of course, whatever the field, needs to bear in mind the necessity of separating ego from opinion. |
Expert error |
Against this background some alarm has been generated in recent years
by a number of cases in the United Kingdom and Australia in which a
miscarriage of justice (that is to say, a wrong result) has occurred as
a result of the admission of highly dubious scientific evidence. In a
paper which I delivered to the Australian Academy of Forensic
Sciences in 199116 I cited
the "Chamberlain Case" in Australia, in which a Royal Commission
finally established that some of the vital evidence for the
prosecution was simply wrong;17
the case of "The Birmingham Six" in England where, again, the
scientific evidence and the methodology used to produce it were
fatally flawed;18,19 and
finally the case of "McLeod-Lindsay", in which scientific
developments subsequent to the trial refuted the evidence upon which
the case for the prosecution largely depended.20
The question raised by instances of this kind is how does "bad" scientific evidence -- what is known as "junk science" in the United States -- get into the court room? How does it find its way into evidence and thus into the deliberations of the tribunal? Some commentators would answer that instantly by ascribing it to judicial incompetence, and the evasion by judges of their responsibility to evaluate expert testimony.21 Another view is that "scientific test evidence is frequently misused in criminal trials because of its unreliability".22 I think that the problem is complex, but I do not have the space here to analyse it. However, it is possible that the judges are about to modify their methods of dealing with expert evidence. |
Judging the experts |
A recent decision of the United States Supreme Court (Daubert v
Merrell Dow Pharmaceuticals) has changed the test for admission
of expert evidence in United States Federal Courts.1 Before that judgment was published,
the test for the admission of expert evidence was much the same as that
in Australia. In the case Frye v United States the test
enunciated was that expert testimony was admissible if it was
"deduced from a well recognised scientific principle or discovery,
the thing from which the deduction is made [being] sufficiently
established to have gained general acceptance in the particular
field to which it belonged".23
Some commentators have expressed the view that there is a
relatively close resemblance between the Frye test and the
principles of admissibility employed in Australia.24,25 But there are contrary views as
well.26,27
The decision in Daubert addressed the issue whether a small group of "impressively credentialled" scientists and doctors could present evidence which seemed to be scientific, but was of too recent origin to have been generally accepted.24 The majority judgment established two criteria for the admissibility of expert evidence: relevance and reliability. It was thus for the judge to ensure that all scientific testimony in evidence "is not only relevant, but reliable" (Daubert at 2795).1 The judges suggested four indicators for assessing whether the testimony met the test of reliability. These were whether the assertion can be and has been tested (i.e., whether it was capable, in Popper's terms, of falsification); whether the theory or technique has been subjected to peer review and publication; the known or potential rate of error; and whether there has been "general acceptance" within a relevant scientific community.24 The effect of Daubert is to impose upon the judge the task of assessing the reliability of a scientific opinion. If the Daubert test is accepted in Australia, the change may be described as transforming "the criteria for admissibility of scientific knowledge claimed, from one based on an expert community's 'general acceptance' of a particular theory to a focus upon the internal practices of the various sciences in combination with certain professional checks and balances such as peer review and error rate in conjunction with consideration of 'general acceptance'".24 It has been said that the shift in legal practice in the United States has transformed the role of the judge "from relatively passive assessor to an active inquisitor searching for the underlying essence of scientific knowledge claims".24 Regarding this, my question is whether this responsibility can be discharged by a judge working within the constraints of the adversarial system. I would think that there may be cases in which the judge, in order to evaluate the scientific evidence, would need to seek the assistance of interim instruction, as I might call it, to provide some basis of knowledge from which to understand the further processes which had produced the opinion offered. Assume, for example, that a judge must examine the reliability of an opinion about the cause of some cardiac condition. It is likely that the judge would need some instruction in basic medical theory and practice in order to understand the process of experiment, observation, and reasoning which has led to the theory from which the final opinion has been deduced. If a judge is confined to the evidence which the parties place before him or her, this process of instruction will be extremely difficult to manage. On the other hand, if every trial in which expert evidence is to be adduced involves subjecting the judge to a crash course of physiological, pathological or anatomical instruction, the trial will be infinitely prolonged and judges very rapidly exhausted. Questions of expert evidence and the difference between the scientific and the legal approach are, I think, both fascinating and critical in the administration of justice. The problem of how a judge is to choose between two scientific witnesses, each of whom appears to be thoroughly well qualified but who cannot agree upon a single particular, is one of perennial difficulty. The attempt to solve it by the device of relying upon the witness's demeanour, although championed by the High Court,28,29 is, in my respectful view, greatly open to question. But the growing incidence of novel medical and other scientific theories -- in particular, the challenge offered by syndrome evidence, leading to what has been called "forensic abuse syndrome"30 -- requires novel modes of judicial response. |
References |
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Originally delivered as the 1997 AMA (NSW) Oration in the Great Hall of the University of Sydney, Tuesday, 17 June 1997.
Correspondence: The Honourable Gordon Samuels, Governor of New South Wales, Macquarie Street, Sydney, NSW 2000.
Allan D Spigelman and Peter Dwyer. Is there a link between work-related stress and colorectal cancer? Med J Aust 2004; 180 (7): 339-340. [Medicine and the Law] <http://www.mja.com.au/public/issues/180_07_050404/spi10205_fm.html>
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