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A Lawyer Looks at Forensic Science: The Expert in Court
3. Forens. Sci. Soc.
(1978), 18, 5
A Lawyer Looks at Forensic Science: The Expert in Court ALISTAIR R. BROWNLIE, Solicitor Supreme Courts, Edinburgh. This paper, the 3rd James Brierley Firth Memorial Lecture, was presented at the Society's Autumn Meeting at the City of London Police Station, Wood Street, London, on Friday, 4 November 1977. James Brierley Firth in whose memory this bi-annual lecture was inaugurated was first President of the Forensic Science Society. He was as I remember him an essentially business-like and down to earth Northerner. What little is revealed of him in the published record (Firth, 1960) portrays an enquiring and resourceful mind, captivated as he himself said, by science. The amusing story of his schoolboy match-box collection of spiders which escaped about his person when he was on the point of demonstrating the lethal effect of carbon dioxide upon them shows him in his earliest days as a practical lad. For him the point of the exercise was to achieve a particular and demonstrable result by the application of science. His subsequent history as a student at Manchester College of Technology, an undergraduate and graduate a t Manchester University and a chemistry lecturer at Armstrong College Newcastle upon Tyne and later at Nottingham University bore this out. Despite the scholarships and the honours which he won he was no pure scientist; no inhabitant of the ivory tower. Nothing could be further from the academic pastures than his later Government explosives work as a chemist on the premises of the Newcastle and Gateshead Gas Company or his consultancy work for the River Purification Board where his studies were of effluents and sewerage. But in 1938 the man matched the hour when he was appointed to direct the newly created North West Forensic Science Laboratory; when as he wrote "my sideline became my job". The record of that engagement is contained in the series of cases which he led his laboratory to solve, particularly in the realm of arson and fire damage investigation and of murder including notably murder by poisoning. Not least among his achievements can be reckoned his foresight in affording leadership and encouragement to the formation of the Forensic Science Society at a time when a lesser man would have backed down because others were known to have something similar in mind. I like to think myself a practical lawyer more interested in the neat disposal of a problem than in theoretical discussion of it and so I reckon it an enduring mark of Dr. Firth's personality that this Society has always represented those who actually work in the field of forensic science as against those who merely theorise about it. And to my mind-although there is nothing wrong with academic study in its proper sphere-there is much to be said for the practical approach. I deem it a greater honour to have been associated albeit in the very smallest and remotest way with Dr. Firth in the formation of this Society than to have held high office or a position of prestige in this or in any other. But in choosing a topic on which to speak to you to-day I could not pass beyond an arresting sentence in the Preamble to Dr. Firth's little book A Scientist turns to Crime. "Nothing has disappointed me more" he wrote "than to go into the witness box with my scientific evidence and find that very often the opposing Counsel could not even attempt to tear holes in it". This sentence encapsulates several of the problems of the application of forensic science as it is understood today and I propose to spend a few minutes examining these
problems because I believe that they are as real and should be as troubling to us as they were to Dr. Firth when that sentence was first penned.
Control by Lawyers The technical aspects of forensic science which are the aspects familiar to most of you present in this audience are one thing. The tosicologists for example naturally discuss analytical methods, the dazzling array of poisons, the proliferating range of food additives, the rapidly multiplying intoxications by drugs almost too numerous to mention. The forensic photographers discuss among themselves the virtues of particular cameras, individual films and different techniques of exposure or developing or printing. And so on. But unlike any of the particular sciences forensic science is peculiar in that it reaches its point of impact only through the intervention of members of another-and as regards training, different-profession : the profession of the law. Whatever wonders the scientist may have performed in the laboratory; whatever identifications or exclusions are made at the scene of the crime; whatever deductions are drawn from examination of materials or by instrumental methods-all have to be reduced to facts and opinions which are eventually put to or drawn from witnesses or at least the written statements of witnesses in Court by lawyers, and adjudicated upon either by lawyers or by a body of laymen closely guided in that event by a bewigged super-lawyer. And so the legal aspects of forensic science are equally important and deserve as careful study as the technical aspects. This puts the forensic scientist in a peculiarly dependent position with regard to the lawyer, and the lawyer in a peculiarly vulnerable position with regard to the scientist. So although the technical aspects of forensic science are one thing, the delivery of the goods in Court is quite another. What can go wrong at the point of delivery causing the expert to be disappointed by the reception his evidence receives? T o answer this question I must recapitulate. Trial at Law The adversary system which we retain in the United Kingdom for resolution of almost all our litigation is a logical enough though somewhat formal framework for enquiry. The trial a t law is not a pursuit of truth in the fullest sense (Napley, 1968). The question at issue is posed for the Court-for example in a damages action arising out of a personal injury claim in some such terms as "whether the accident in which the claimant was injured on 15 December 1976 was to any extent caused by the fault of the defendant: and if so to what extent?" A claim for payment of a debt is an enquiry into the question "whether the defendant is indebted to the claimant and if so to what extent". A criminal case is an examination of the proposition "that at a particular place and time the accused stabbed the victim in the chest with a knife and did murder him". Since the framing of the question conditions the answer to be given, the direction and scope of the enquiry lie to some considerable extent under the control of the prosecutor or the claimant. At the trial the prosecution produce whatever evidence they have to support the proposition in the affirmative while the defence adduce what evidence, if any, they have to negative the proposition. And unless the prosecution prevail in supporting their proposition to the required standard of proof beyond reasonable doubt they have failed to prove their assertions, there is no conviction and the accmed is entitled to an acquittal. Relevancy The scope of the enquiry at proof or trial is of course also limited by logical bounds. The lawyer's concept of relevancy is simply the legal rule recognizing the pointlessness of allowing evidence which does not go in any degree to support or negative the issue. Where the question is whether A stabbed B evidence that A is a shoplifter and a liar is irrelevant because even if it were
admitted and established it would not tend either to prove or to disprove the issue in the case. At his recent press conference arising out of the unhappy allegations of Norman Scott who claimed amongst other things a homosexual relationship with the former leader of the Liberal Party Mr. Jeremy Thorpe was pointedly asked by one of the least inhibited of the news reporters present (according to a television commentary which I recall watching) "Are you a homosexual?" The question was said to have been disallowed by the Chairman as being irrelevant and a gross invasion of privacy. An invasion of privacy it may have been but the question was relevant. One who is not a homosexual can hardly have a homosexual relationship. And so at least an answer in the negative would have tended to help towards resolving the matter at issue. Admittedly an answer in the affirmative would have elicited evidence more prejudicial than probative-for to say X is a homosexual is not to say that X enjoyed a homosexual relationship with Y who so alleges. I t merely puts X into the category of persons who might have had such a relationship. But of course a press conference is not a trial. Lawyers sometimes have to curb scientific evidence on the grounds that the enquiry is ranging too far afield, and that even if the evidence were accepted in its entirety it would not significantly assist to answer the issue in the case and that it is irrelevant. Obviously the scientist who feels he is on the track of a solution to his problem will not wish to be inhibited by an artificial legal barrier. In presenting scientific evidence it is always necessary to keep clearly in view what it is hoped to establish by the evidence. By that of.course I do not mean that the expert witness should tailor or trim his evidence to bring it round to supporting the case of the person who called him. Not infrequently the crisp point of the evidence is lost in the (to the Court) unfamiliar technical detail. The well known warning sign when the judge testily enquires of Counsel "Mr. Lustgarten-where is all this leading us?" is a clear indication that relevancy is at risk and that it is necessary at once to concentrate on the wood and try to direct the Court's attention past the trees. I t may also signify that Counsel who is leading the expert witnesses through his evidence may not appreciate precisely what is the objective of the evidence or what it is expected to achieve. I n such a situation it is helpful for the witness himself to say "The point I am seeking to make is that the bullet wound in the back of the head could not have been self-inflicted for the following reasons. . ." (or to summarise whatever the point may be).
Introduction to the Evidence I t is one of the differences between English and Scottish criminal procedure that in an English jury trial the prosecutor will open the case with an introductory statement of what he intends to prove. "I shall bring before you" he will say magnificently to the jury "the evidence of that brilliant pathologist Dr. X who will explain to you the autopsy findings which conclusively show that at the time of his death the deceased's stomach contained the remains of an apple dumpling consumed no more than 35 minutes before his strangulation at the hands of his shrewish wife." Such an explanation is probably a useful introduction to the English jury whose counterparts in Scotland would be plunged without a word of explanation into the evidence of Dr. X who to their amazement is suddenly and unaccountably heard to be describing his faintly disgusting investigation of stomach contents. Where the English system goes wrong of course is when the actual evidence for one reason or another fails to come up to the forecast of it supplied by Counsel. I n such a case the jury may well be left with a memory of the description ofwhat the witness would say rather than the lesser import of what the witness actually did say. This represents another situation where the result for the expert must be less than satisfactory.
Expert Testimony It is trite to say that expert testimony differs from ordinary evidence in at least
two respects. The ordinary witness is not allowed to express an opinion-merely to state facts of which he has personal knowledge. But the expert witness (assuming that he is qualified and that his evidence is admissible) may state both the facts within his knowledge and his opinion based upon these facts illustrated and supported by his experience in his specialty. He will probably be allowed to illustrate his evidence by the use of photographs, charts, even instruments and audio or visual aids (Garner, 1960; Davis et al., 1961 ; B.M.A. Report, 1965; Belli, 1968; Cato, 1974). I t is vital for the expert witness to distinguish fact and opinion, to be able to vouch the facts and to justify the opinion as well founded, moderate and reasonable, and effectively to project that opinion. I t is of the utmost assistance to the Court when the expert is also able to determine the degree of confidence that may be assigned to a particular opinion and, as Ormrod has said "The one essential of all expert evidence is a frank statement by the expert of the limits of accuracy within which he is speaking and a readiness to indicate whether asked or not, what his evidence does not prove or suggest as likely." (Ormrod, 1968; 1972) The evidence of an expert is usually challenged in one of two ways: either the soundness of the conclusions drawn from the known or assumed facts is impugned, or the cross-examiner may ask the expert for his opinion on the facts as the cross-examiner hopes to establish them. This involves the hypothetical question and a crystal gazing exercise which is not permitted to ordinary witnesses and forms one of the major bugbears of the expert. Of course if the facts on which an opinion is based are vulnerable the whole opinion may be vitiated. Normally the main outlines of the case are set up by other evidence and the expert's part in the proceedings is simply to supply one or two threads in the warp and woof of evidence, though these are usually indispensible threads. So in the insulin murder case of H. M. Advocate v. Jessie McTavish (H. M. Adv. v McTavish, 1974) decided in October 1974 in Edinburgh some fourteen days were spent in Court laboriously establishing the timetable of events followed by Nurse McTavish in attending to the patients in her geriatric ward, the degree of supervision and the instructions given by the doctors and the sequence and nature of the injections administered to patients. The really critical scientific evidence concerned the post-mortem findings, the injections of insulin which must have been necessary to account for the post-mortem traces and the comparison of these quantities with the known lethal dosage all of which technical evidence was covered according to my recollection in less than two days. I t was no fault of the experts that the lady's conviction was later set aside because of a flaw in the judge's charge to the jury.
Giving - Evidence If it is true that lawyers and scientists tend to be ignorant of each other's methods and aims it is also true that some of the antipathy between them is attributable to the lawyers' failure to explain to the scientists the nature of the exercise. Too often the expert witness is propelled into the witness box without adequate consideration of what is the purpose of the evidence and the reasons for his public examination thereon. Every lawyer knows that careful preparation for a trial pays dividends and this applies with especial force to the expert witness if he is to survive the ordeal with his confidence unshaken. The expert witness must examine and re-examine his evidence for flaws: he must hone it down to its essentials and he must express these essentials in language which the lawyers, judge and jury, can comprehend. Inability to do so will result in the failure of communication between parties noted by Dr. Firth. The ability to give evidence briefly, pointedly and with conviction is a skill to be worked at and developed and everything that contributes to a satisfactory result is to be commended. The witness should look the part: he should
respond with quiet dignity to the questions put by Counsel, speaking in a clear confident voice loud enough to be heard by all in Court, he should be prepared without immodesty to exhibit in his answers the experience which presumably he has of his subject (Walls, 1972). An ability to introduce a touch of humour at the right point or better still to respond should judge or Counsel strike such a note is immensely helpful to release tension. Some slight acting ability will not go amiss. Even the weather forecasters who explain the daily weather prospects on television add interest to their rather repetitive account by moving a little, by pointing to the areas they are describing or by affixing a symbolic rain cloud over the Manchester district as they explain the precipitation likely to be brought about by the approaching cold front. These little touches which add interest to the presentation are not to be despised because the aim is to give evidence truthfully, memorably, effectively and well. I t is desirable however to avoid histrionics. The doctor who was persuaded in the case of Dr. John Bodkin Adams in 1957 to demonstrate a "withdrawal fit" such as might follow the withdrawal of morphine or heroin from an addict was later forced to admit that he had never in his life seen such an attack (Simpson, 1962). Although the subject of the evidence may be a most technical matter it should be possible to reduce it to manageable proportions. All human knowledge ought to be capable of formulation in propositions which an educated person, having taken sufficient trouble, can understand. In my view the Court have no right to accept expert testimony which cannot be brought to this state. T o do otherwise and pass evidence which is incomprehensible would be to revert to the days of witchcraft and magic. We have often spoken before in this Society (Grant, 1966; Simpson, 1969; Watson, 1975) of the need for adequate consultation before a proof or trial between Counsel or Solicitor and his expert witness. The purpose of such a consultation which is not only permissible but virtually indispensable would be to make sure that Counsel understands the import of the evidence; to decide the order and emphasis to be accorded to the evidence; to rehearse, it may be, the terms in which the technical aspect is to be communicated moderately and fairly, and perhaps to meet in advance and discuss any possible criticism or challenge that is likely to be brought against it. Careful attention to these aspects of the evidence will pay dividends in making sure that questioner and witness are on the same wavelength, understanding one another, if not actually agreeing, and avoiding unnecessary tension. I t is often said that the question and answer method of eliciting evidence is unsuited to expert testimony. Certainly much evidence is now given as the result of the Civil Evidence Act 1972 in written form, but even when this is not so a written presentation is a useful way of accelerating the giving of evidence, the whole report first being referred to and question and answer then expanding on the conclusions reached. I n Scotland where all factual evidence has to be corroborated (for there even the traffic wardens hunt in pairs) it is normal for a joint medical report to be submitted as the basis of evidence-in-chief of the two pathologists who conducted the autopsy. But properly handled question and answer should lead logically and surely to the appropriate climax, though one must remember the dictum of one American textbook: "To get an intelligent answer one must ask an intelligent question." (Moenssens ct al., 1973).
Cross Examination Cross examination seems to me the part of the proceedings most feared by the witness, not least by the expert. Many scientists have not given adequate attention to its purpose. The legal attitude is that cross examination is the means of testing the validity of the conclusions expressed by the witness: it is themeans of reducing or eliminating the danger that a false conclusion is reached; it has been known to reduce pretensions; its aim is to reveal the truth. And properly used it is a powerful technique. Where a witness is speaking the truth or expressing a well-founded opinion a thorough testing by cross examination should serve only
to enhance the standing of the witness and demonstrate the objectivity and integrity of his evidence. I t is the overwhelming belief of lawyers that the technique is as effective for resolving technological issues as it is for resolving issues arising from the ordinary affairs of the man in the street. (Sive, 1974) Not every scientist has agreed. (Patterson, 1975) I am only too well aware that second-rate cross examination including abusive tactics, derogatory or belittling remarks or deliberate misleading of the Court have been too commonly used and these are improper. (Colman, 1970) A witness who is hectored by the cross-examiner may appeal to the Court for help, but the honest witness whose opinions are modestly asserted and patiently explained is unlikely to suffer. If the candid objective and competent expert refuses to appear in the forensic setting he merely leaves the field open to the less candid objective and competent to appear which is regrettable. (Samuels, 1974) In particular I would like to remind the expert witness that he should never allow himself to be forced into answering a question in terms which cannot constitute a truthful response. The obligation of the witness is to tell the truth, the whole truth, and although the questioner is entitled to press his questions the witness is equally entitled to reply that no meaningful answer to such questions is possible. The Court will always afford an opportunity for the witness at the end of his testimony to add his own comment. If he is able to do so in a brief and clear fashion he may be able to show that the questioner does not understand the subject and so that his questions are valueless. This is probably the point at which, if Counsel has failed to prepare himself, the evidence becomes a meaningless tangle. No communication is likely to result where transmitter and receiver are tuned to different wavelengths. - -
Words To achieve a lucid presentation of evidence-particularly expert evidence-it is necessary to pay the greatest attention to the words in which the expert formulates his testimony. There must be a clear understanding of the meaning of the terms used and both witness and lawyer must use the terms in the same sense. The controlling influence of language upon all Court proceedings and the absolute necessity for both lawyer and expert witness to have a facility and skill with words is material for a second memorial lecture if not for a series of lectures. Jonathan Swift took the point (though in a most uncomplimentary way) when he described lawyers as "a society of men bred up from youth in the art of proving by words multiplied for the purpose that white is black and black is white according as they are paid." I n order to have the arguments for and against the trial issue marshalled and laid out it is necessary for the competing views to be expressed as eloquently and as precisely as may be. And what goes for the lawyer goes too for the expert witness. A similar message was conveyed in 1820 to a wider audience by William Cobbett who published his full-titled: "Grammar of the English Language in a series of letters intended for the use of schools and of young persons in general; but more especially for the use of soldiers, sailors, apprentices and ploughboys to which are added six lessons intended to prevent statesmen from writing in an awkward manner". In this book he conveys much good advice eminently suited to the witness, criticising those who use language in a vague way and concluding "let chambermaids and members of the House of Commons and learned doctors write thus. Be you content with plain words which convey your meaning." The possibility of gradually introducing Courts to statistical probability evidence is a matter which has been discussed on several occasions in this Society. (Walls, 1966) I t is already given in a limited way particularly with regard to blood group evidence. The difficulty however is that lawyers have no skill in understanding the mathematics of probability, and that most types of evidence as yet lack an evaluation of their fundamental statistical data (Biasotti, 1964; Kirk and Kingston, 1964).
Failure to test the Evidence I n the last resort the unwillingness of Counsel to join issue with the expert which Dr. Firth complained about may have been due to an entire acceptance of that evidence. Most experts thankfully welcome this situation, but I take it as a mark of Dr. Firth's understanding and approval of the legal procedures of trial, examination and cross examination that he felt cheated when his evidence was not subjected to the stress of challenge. I n truth however the reluctance of Counsel to challenge it was much more likely to have been due to their inability fully to understand it or to know how or where to repair that ignorance. To question what you do not understand is much more likely to bring about a reinforcement of the original evidence than to modify its force. This brings me back to a problem on which I have previously spoken to this Society concerning the apparent reluctance of lawyers to interest themselves in matters of forensic science (Brownlie 1972). Much remains to be done in this field where the virtual absence of the lawyer is rightly seen as pointing to a deficiency in his training in that no preparation was given to enable him to understand the aims and methods of his professional counterparts in the medical and scientific professions. Things are however beginning to move as more and more expert evidence is given in our Courts. The legal membership of our Society is slowly increasing, the involvement of lawyers along with scientists in our meetings is somewhat improved and the Society is now giving consideration to some activity in the field of education which will hopefully begin to touch and influence professionals of the different disciplines in coming years. If communication between lawyers and scientists is opened up both in Court and out of it I hope I have shown that such an achievement would be one of which Dr. James Brierley Firth would have enthusiastically approved. References BELLI,M. H., 1968, Forensic Medical Experts, Obligations and Responsibility, Med. Sci. Law., 8, 15-23. BIASOTTI,A. A., 1964, Principles of Evidence and Evaluation as applied to Firearms and Tool Mark Identification, 3. For. Sci., 9,428. B. M. A. REPORT,1965, Medical Evidence in Courts of Law, Report of a Joint Committee, B.M.A., London. BROWNLIE, A. R., 1972, Where have all the Lawyers Gone, 3.Forens. Sci. Soc. 12,547-552. CATO,B. H., 1974, The Presentation of Scientific Evidence in Court-Improving its Effectiveness, 3.Forens. Sci. Soc., 14, 93-98 COLMAN,G., 1970, Cross Examination: A Practical Handbook, Cape Town: Juta and Co. Ltd. DAVIS, J. G., SIMPSON, K. AND CAPLIN, L., 1961 Colloquium : The Expert Witness, J. Forens. Sci. Soc., 2, 19-26. FIRTH,J. B. 1960, A Scientist Turtls to Crime, London, Wm. Kimber. GARNER, W., 1960, An Expert looks at the Courts, 3.Forens. Sci. Soc., 1, 69-78. GRANT,J., 1966, The Future of Forensic Science, Med. Sci. Law, 6, 206-209. H. M. ADV. v. MCTAVEH,1974, High Court of Justiciary, Edinburgh, 17 September to 7 October 1974. KIRK,P. L. AND KINGSTON, C. R., 1964, Evidence Evaluation and Problems in General Criminalistics, 3. For. Sci., 9, 434. MOENSSENS, A. A., MOSESR. E. AND INBAU,F. E., 1973, ScientiJicEvidence in Criminal Cases, p. 13, New York, Foundation Press. NAPLEY,D., 1968, Trial at Law, Med. Sci. Law., 8,227. ORMROD: R., 1968, Scientific Evidence in Court (1968) Crim. L. R., 240-247. ORMROD, R., 1972, Evidence and Proof: Scientific and Legal, Med. Sci. Law., 12, 9-'20. 1I
PATTERSON, D., 1975, What can Science do for the Law? J. Forens. Sci .SOC., 15, 5. SAMUELS, A., 1974, Expert Forensic Evidence, Med. Sci, Law, 14, 17-25. ON TESTIMONY, 1957a, Effective Expert Testimony, J . For. Sci., 2, SEMINAR 73-93; 1957b, 177-193. SIMPSON, K., 1962, A Doctor's Guide to Court, p48, London, Butterworth. SIMPSON, K., 1969, The Art of Forensic Pathology, J . Forens. Sci. Soc., 9, 199. SIVE,D., 1974, Scientists in the Courtroom, In Scientists in the Legal System, Thomas, W. A., An Arbor Scientific Publishers. WALLS,H. J., 1966, Whither Forensic Science, Med. Sci. Law, 6, 183-189. WALLS,H. J., 1972, Expert Witness, London, John Long. J. A. F., 1975, Nothing but the Truth: Expert Evidence in Principle and WATSON, Practice, Estates Gazette, London.
(1978), 18, 5
A Lawyer Looks at Forensic Science: The Expert in Court ALISTAIR R. BROWNLIE, Solicitor Supreme Courts, Edinburgh. This paper, the 3rd James Brierley Firth Memorial Lecture, was presented at the Society's Autumn Meeting at the City of London Police Station, Wood Street, London, on Friday, 4 November 1977. James Brierley Firth in whose memory this bi-annual lecture was inaugurated was first President of the Forensic Science Society. He was as I remember him an essentially business-like and down to earth Northerner. What little is revealed of him in the published record (Firth, 1960) portrays an enquiring and resourceful mind, captivated as he himself said, by science. The amusing story of his schoolboy match-box collection of spiders which escaped about his person when he was on the point of demonstrating the lethal effect of carbon dioxide upon them shows him in his earliest days as a practical lad. For him the point of the exercise was to achieve a particular and demonstrable result by the application of science. His subsequent history as a student at Manchester College of Technology, an undergraduate and graduate a t Manchester University and a chemistry lecturer at Armstrong College Newcastle upon Tyne and later at Nottingham University bore this out. Despite the scholarships and the honours which he won he was no pure scientist; no inhabitant of the ivory tower. Nothing could be further from the academic pastures than his later Government explosives work as a chemist on the premises of the Newcastle and Gateshead Gas Company or his consultancy work for the River Purification Board where his studies were of effluents and sewerage. But in 1938 the man matched the hour when he was appointed to direct the newly created North West Forensic Science Laboratory; when as he wrote "my sideline became my job". The record of that engagement is contained in the series of cases which he led his laboratory to solve, particularly in the realm of arson and fire damage investigation and of murder including notably murder by poisoning. Not least among his achievements can be reckoned his foresight in affording leadership and encouragement to the formation of the Forensic Science Society at a time when a lesser man would have backed down because others were known to have something similar in mind. I like to think myself a practical lawyer more interested in the neat disposal of a problem than in theoretical discussion of it and so I reckon it an enduring mark of Dr. Firth's personality that this Society has always represented those who actually work in the field of forensic science as against those who merely theorise about it. And to my mind-although there is nothing wrong with academic study in its proper sphere-there is much to be said for the practical approach. I deem it a greater honour to have been associated albeit in the very smallest and remotest way with Dr. Firth in the formation of this Society than to have held high office or a position of prestige in this or in any other. But in choosing a topic on which to speak to you to-day I could not pass beyond an arresting sentence in the Preamble to Dr. Firth's little book A Scientist turns to Crime. "Nothing has disappointed me more" he wrote "than to go into the witness box with my scientific evidence and find that very often the opposing Counsel could not even attempt to tear holes in it". This sentence encapsulates several of the problems of the application of forensic science as it is understood today and I propose to spend a few minutes examining these
problems because I believe that they are as real and should be as troubling to us as they were to Dr. Firth when that sentence was first penned.
Control by Lawyers The technical aspects of forensic science which are the aspects familiar to most of you present in this audience are one thing. The tosicologists for example naturally discuss analytical methods, the dazzling array of poisons, the proliferating range of food additives, the rapidly multiplying intoxications by drugs almost too numerous to mention. The forensic photographers discuss among themselves the virtues of particular cameras, individual films and different techniques of exposure or developing or printing. And so on. But unlike any of the particular sciences forensic science is peculiar in that it reaches its point of impact only through the intervention of members of another-and as regards training, different-profession : the profession of the law. Whatever wonders the scientist may have performed in the laboratory; whatever identifications or exclusions are made at the scene of the crime; whatever deductions are drawn from examination of materials or by instrumental methods-all have to be reduced to facts and opinions which are eventually put to or drawn from witnesses or at least the written statements of witnesses in Court by lawyers, and adjudicated upon either by lawyers or by a body of laymen closely guided in that event by a bewigged super-lawyer. And so the legal aspects of forensic science are equally important and deserve as careful study as the technical aspects. This puts the forensic scientist in a peculiarly dependent position with regard to the lawyer, and the lawyer in a peculiarly vulnerable position with regard to the scientist. So although the technical aspects of forensic science are one thing, the delivery of the goods in Court is quite another. What can go wrong at the point of delivery causing the expert to be disappointed by the reception his evidence receives? T o answer this question I must recapitulate. Trial at Law The adversary system which we retain in the United Kingdom for resolution of almost all our litigation is a logical enough though somewhat formal framework for enquiry. The trial a t law is not a pursuit of truth in the fullest sense (Napley, 1968). The question at issue is posed for the Court-for example in a damages action arising out of a personal injury claim in some such terms as "whether the accident in which the claimant was injured on 15 December 1976 was to any extent caused by the fault of the defendant: and if so to what extent?" A claim for payment of a debt is an enquiry into the question "whether the defendant is indebted to the claimant and if so to what extent". A criminal case is an examination of the proposition "that at a particular place and time the accused stabbed the victim in the chest with a knife and did murder him". Since the framing of the question conditions the answer to be given, the direction and scope of the enquiry lie to some considerable extent under the control of the prosecutor or the claimant. At the trial the prosecution produce whatever evidence they have to support the proposition in the affirmative while the defence adduce what evidence, if any, they have to negative the proposition. And unless the prosecution prevail in supporting their proposition to the required standard of proof beyond reasonable doubt they have failed to prove their assertions, there is no conviction and the accmed is entitled to an acquittal. Relevancy The scope of the enquiry at proof or trial is of course also limited by logical bounds. The lawyer's concept of relevancy is simply the legal rule recognizing the pointlessness of allowing evidence which does not go in any degree to support or negative the issue. Where the question is whether A stabbed B evidence that A is a shoplifter and a liar is irrelevant because even if it were
admitted and established it would not tend either to prove or to disprove the issue in the case. At his recent press conference arising out of the unhappy allegations of Norman Scott who claimed amongst other things a homosexual relationship with the former leader of the Liberal Party Mr. Jeremy Thorpe was pointedly asked by one of the least inhibited of the news reporters present (according to a television commentary which I recall watching) "Are you a homosexual?" The question was said to have been disallowed by the Chairman as being irrelevant and a gross invasion of privacy. An invasion of privacy it may have been but the question was relevant. One who is not a homosexual can hardly have a homosexual relationship. And so at least an answer in the negative would have tended to help towards resolving the matter at issue. Admittedly an answer in the affirmative would have elicited evidence more prejudicial than probative-for to say X is a homosexual is not to say that X enjoyed a homosexual relationship with Y who so alleges. I t merely puts X into the category of persons who might have had such a relationship. But of course a press conference is not a trial. Lawyers sometimes have to curb scientific evidence on the grounds that the enquiry is ranging too far afield, and that even if the evidence were accepted in its entirety it would not significantly assist to answer the issue in the case and that it is irrelevant. Obviously the scientist who feels he is on the track of a solution to his problem will not wish to be inhibited by an artificial legal barrier. In presenting scientific evidence it is always necessary to keep clearly in view what it is hoped to establish by the evidence. By that of.course I do not mean that the expert witness should tailor or trim his evidence to bring it round to supporting the case of the person who called him. Not infrequently the crisp point of the evidence is lost in the (to the Court) unfamiliar technical detail. The well known warning sign when the judge testily enquires of Counsel "Mr. Lustgarten-where is all this leading us?" is a clear indication that relevancy is at risk and that it is necessary at once to concentrate on the wood and try to direct the Court's attention past the trees. I t may also signify that Counsel who is leading the expert witnesses through his evidence may not appreciate precisely what is the objective of the evidence or what it is expected to achieve. I n such a situation it is helpful for the witness himself to say "The point I am seeking to make is that the bullet wound in the back of the head could not have been self-inflicted for the following reasons. . ." (or to summarise whatever the point may be).
Introduction to the Evidence I t is one of the differences between English and Scottish criminal procedure that in an English jury trial the prosecutor will open the case with an introductory statement of what he intends to prove. "I shall bring before you" he will say magnificently to the jury "the evidence of that brilliant pathologist Dr. X who will explain to you the autopsy findings which conclusively show that at the time of his death the deceased's stomach contained the remains of an apple dumpling consumed no more than 35 minutes before his strangulation at the hands of his shrewish wife." Such an explanation is probably a useful introduction to the English jury whose counterparts in Scotland would be plunged without a word of explanation into the evidence of Dr. X who to their amazement is suddenly and unaccountably heard to be describing his faintly disgusting investigation of stomach contents. Where the English system goes wrong of course is when the actual evidence for one reason or another fails to come up to the forecast of it supplied by Counsel. I n such a case the jury may well be left with a memory of the description ofwhat the witness would say rather than the lesser import of what the witness actually did say. This represents another situation where the result for the expert must be less than satisfactory.
Expert Testimony It is trite to say that expert testimony differs from ordinary evidence in at least
two respects. The ordinary witness is not allowed to express an opinion-merely to state facts of which he has personal knowledge. But the expert witness (assuming that he is qualified and that his evidence is admissible) may state both the facts within his knowledge and his opinion based upon these facts illustrated and supported by his experience in his specialty. He will probably be allowed to illustrate his evidence by the use of photographs, charts, even instruments and audio or visual aids (Garner, 1960; Davis et al., 1961 ; B.M.A. Report, 1965; Belli, 1968; Cato, 1974). I t is vital for the expert witness to distinguish fact and opinion, to be able to vouch the facts and to justify the opinion as well founded, moderate and reasonable, and effectively to project that opinion. I t is of the utmost assistance to the Court when the expert is also able to determine the degree of confidence that may be assigned to a particular opinion and, as Ormrod has said "The one essential of all expert evidence is a frank statement by the expert of the limits of accuracy within which he is speaking and a readiness to indicate whether asked or not, what his evidence does not prove or suggest as likely." (Ormrod, 1968; 1972) The evidence of an expert is usually challenged in one of two ways: either the soundness of the conclusions drawn from the known or assumed facts is impugned, or the cross-examiner may ask the expert for his opinion on the facts as the cross-examiner hopes to establish them. This involves the hypothetical question and a crystal gazing exercise which is not permitted to ordinary witnesses and forms one of the major bugbears of the expert. Of course if the facts on which an opinion is based are vulnerable the whole opinion may be vitiated. Normally the main outlines of the case are set up by other evidence and the expert's part in the proceedings is simply to supply one or two threads in the warp and woof of evidence, though these are usually indispensible threads. So in the insulin murder case of H. M. Advocate v. Jessie McTavish (H. M. Adv. v McTavish, 1974) decided in October 1974 in Edinburgh some fourteen days were spent in Court laboriously establishing the timetable of events followed by Nurse McTavish in attending to the patients in her geriatric ward, the degree of supervision and the instructions given by the doctors and the sequence and nature of the injections administered to patients. The really critical scientific evidence concerned the post-mortem findings, the injections of insulin which must have been necessary to account for the post-mortem traces and the comparison of these quantities with the known lethal dosage all of which technical evidence was covered according to my recollection in less than two days. I t was no fault of the experts that the lady's conviction was later set aside because of a flaw in the judge's charge to the jury.
Giving - Evidence If it is true that lawyers and scientists tend to be ignorant of each other's methods and aims it is also true that some of the antipathy between them is attributable to the lawyers' failure to explain to the scientists the nature of the exercise. Too often the expert witness is propelled into the witness box without adequate consideration of what is the purpose of the evidence and the reasons for his public examination thereon. Every lawyer knows that careful preparation for a trial pays dividends and this applies with especial force to the expert witness if he is to survive the ordeal with his confidence unshaken. The expert witness must examine and re-examine his evidence for flaws: he must hone it down to its essentials and he must express these essentials in language which the lawyers, judge and jury, can comprehend. Inability to do so will result in the failure of communication between parties noted by Dr. Firth. The ability to give evidence briefly, pointedly and with conviction is a skill to be worked at and developed and everything that contributes to a satisfactory result is to be commended. The witness should look the part: he should
respond with quiet dignity to the questions put by Counsel, speaking in a clear confident voice loud enough to be heard by all in Court, he should be prepared without immodesty to exhibit in his answers the experience which presumably he has of his subject (Walls, 1972). An ability to introduce a touch of humour at the right point or better still to respond should judge or Counsel strike such a note is immensely helpful to release tension. Some slight acting ability will not go amiss. Even the weather forecasters who explain the daily weather prospects on television add interest to their rather repetitive account by moving a little, by pointing to the areas they are describing or by affixing a symbolic rain cloud over the Manchester district as they explain the precipitation likely to be brought about by the approaching cold front. These little touches which add interest to the presentation are not to be despised because the aim is to give evidence truthfully, memorably, effectively and well. I t is desirable however to avoid histrionics. The doctor who was persuaded in the case of Dr. John Bodkin Adams in 1957 to demonstrate a "withdrawal fit" such as might follow the withdrawal of morphine or heroin from an addict was later forced to admit that he had never in his life seen such an attack (Simpson, 1962). Although the subject of the evidence may be a most technical matter it should be possible to reduce it to manageable proportions. All human knowledge ought to be capable of formulation in propositions which an educated person, having taken sufficient trouble, can understand. In my view the Court have no right to accept expert testimony which cannot be brought to this state. T o do otherwise and pass evidence which is incomprehensible would be to revert to the days of witchcraft and magic. We have often spoken before in this Society (Grant, 1966; Simpson, 1969; Watson, 1975) of the need for adequate consultation before a proof or trial between Counsel or Solicitor and his expert witness. The purpose of such a consultation which is not only permissible but virtually indispensable would be to make sure that Counsel understands the import of the evidence; to decide the order and emphasis to be accorded to the evidence; to rehearse, it may be, the terms in which the technical aspect is to be communicated moderately and fairly, and perhaps to meet in advance and discuss any possible criticism or challenge that is likely to be brought against it. Careful attention to these aspects of the evidence will pay dividends in making sure that questioner and witness are on the same wavelength, understanding one another, if not actually agreeing, and avoiding unnecessary tension. I t is often said that the question and answer method of eliciting evidence is unsuited to expert testimony. Certainly much evidence is now given as the result of the Civil Evidence Act 1972 in written form, but even when this is not so a written presentation is a useful way of accelerating the giving of evidence, the whole report first being referred to and question and answer then expanding on the conclusions reached. I n Scotland where all factual evidence has to be corroborated (for there even the traffic wardens hunt in pairs) it is normal for a joint medical report to be submitted as the basis of evidence-in-chief of the two pathologists who conducted the autopsy. But properly handled question and answer should lead logically and surely to the appropriate climax, though one must remember the dictum of one American textbook: "To get an intelligent answer one must ask an intelligent question." (Moenssens ct al., 1973).
Cross Examination Cross examination seems to me the part of the proceedings most feared by the witness, not least by the expert. Many scientists have not given adequate attention to its purpose. The legal attitude is that cross examination is the means of testing the validity of the conclusions expressed by the witness: it is themeans of reducing or eliminating the danger that a false conclusion is reached; it has been known to reduce pretensions; its aim is to reveal the truth. And properly used it is a powerful technique. Where a witness is speaking the truth or expressing a well-founded opinion a thorough testing by cross examination should serve only
to enhance the standing of the witness and demonstrate the objectivity and integrity of his evidence. I t is the overwhelming belief of lawyers that the technique is as effective for resolving technological issues as it is for resolving issues arising from the ordinary affairs of the man in the street. (Sive, 1974) Not every scientist has agreed. (Patterson, 1975) I am only too well aware that second-rate cross examination including abusive tactics, derogatory or belittling remarks or deliberate misleading of the Court have been too commonly used and these are improper. (Colman, 1970) A witness who is hectored by the cross-examiner may appeal to the Court for help, but the honest witness whose opinions are modestly asserted and patiently explained is unlikely to suffer. If the candid objective and competent expert refuses to appear in the forensic setting he merely leaves the field open to the less candid objective and competent to appear which is regrettable. (Samuels, 1974) In particular I would like to remind the expert witness that he should never allow himself to be forced into answering a question in terms which cannot constitute a truthful response. The obligation of the witness is to tell the truth, the whole truth, and although the questioner is entitled to press his questions the witness is equally entitled to reply that no meaningful answer to such questions is possible. The Court will always afford an opportunity for the witness at the end of his testimony to add his own comment. If he is able to do so in a brief and clear fashion he may be able to show that the questioner does not understand the subject and so that his questions are valueless. This is probably the point at which, if Counsel has failed to prepare himself, the evidence becomes a meaningless tangle. No communication is likely to result where transmitter and receiver are tuned to different wavelengths. - -
Words To achieve a lucid presentation of evidence-particularly expert evidence-it is necessary to pay the greatest attention to the words in which the expert formulates his testimony. There must be a clear understanding of the meaning of the terms used and both witness and lawyer must use the terms in the same sense. The controlling influence of language upon all Court proceedings and the absolute necessity for both lawyer and expert witness to have a facility and skill with words is material for a second memorial lecture if not for a series of lectures. Jonathan Swift took the point (though in a most uncomplimentary way) when he described lawyers as "a society of men bred up from youth in the art of proving by words multiplied for the purpose that white is black and black is white according as they are paid." I n order to have the arguments for and against the trial issue marshalled and laid out it is necessary for the competing views to be expressed as eloquently and as precisely as may be. And what goes for the lawyer goes too for the expert witness. A similar message was conveyed in 1820 to a wider audience by William Cobbett who published his full-titled: "Grammar of the English Language in a series of letters intended for the use of schools and of young persons in general; but more especially for the use of soldiers, sailors, apprentices and ploughboys to which are added six lessons intended to prevent statesmen from writing in an awkward manner". In this book he conveys much good advice eminently suited to the witness, criticising those who use language in a vague way and concluding "let chambermaids and members of the House of Commons and learned doctors write thus. Be you content with plain words which convey your meaning." The possibility of gradually introducing Courts to statistical probability evidence is a matter which has been discussed on several occasions in this Society. (Walls, 1966) I t is already given in a limited way particularly with regard to blood group evidence. The difficulty however is that lawyers have no skill in understanding the mathematics of probability, and that most types of evidence as yet lack an evaluation of their fundamental statistical data (Biasotti, 1964; Kirk and Kingston, 1964).
Failure to test the Evidence I n the last resort the unwillingness of Counsel to join issue with the expert which Dr. Firth complained about may have been due to an entire acceptance of that evidence. Most experts thankfully welcome this situation, but I take it as a mark of Dr. Firth's understanding and approval of the legal procedures of trial, examination and cross examination that he felt cheated when his evidence was not subjected to the stress of challenge. I n truth however the reluctance of Counsel to challenge it was much more likely to have been due to their inability fully to understand it or to know how or where to repair that ignorance. To question what you do not understand is much more likely to bring about a reinforcement of the original evidence than to modify its force. This brings me back to a problem on which I have previously spoken to this Society concerning the apparent reluctance of lawyers to interest themselves in matters of forensic science (Brownlie 1972). Much remains to be done in this field where the virtual absence of the lawyer is rightly seen as pointing to a deficiency in his training in that no preparation was given to enable him to understand the aims and methods of his professional counterparts in the medical and scientific professions. Things are however beginning to move as more and more expert evidence is given in our Courts. The legal membership of our Society is slowly increasing, the involvement of lawyers along with scientists in our meetings is somewhat improved and the Society is now giving consideration to some activity in the field of education which will hopefully begin to touch and influence professionals of the different disciplines in coming years. If communication between lawyers and scientists is opened up both in Court and out of it I hope I have shown that such an achievement would be one of which Dr. James Brierley Firth would have enthusiastically approved. References BELLI,M. H., 1968, Forensic Medical Experts, Obligations and Responsibility, Med. Sci. Law., 8, 15-23. BIASOTTI,A. A., 1964, Principles of Evidence and Evaluation as applied to Firearms and Tool Mark Identification, 3. For. Sci., 9,428. B. M. A. REPORT,1965, Medical Evidence in Courts of Law, Report of a Joint Committee, B.M.A., London. BROWNLIE, A. R., 1972, Where have all the Lawyers Gone, 3.Forens. Sci. Soc. 12,547-552. CATO,B. H., 1974, The Presentation of Scientific Evidence in Court-Improving its Effectiveness, 3.Forens. Sci. Soc., 14, 93-98 COLMAN,G., 1970, Cross Examination: A Practical Handbook, Cape Town: Juta and Co. Ltd. DAVIS, J. G., SIMPSON, K. AND CAPLIN, L., 1961 Colloquium : The Expert Witness, J. Forens. Sci. Soc., 2, 19-26. FIRTH,J. B. 1960, A Scientist Turtls to Crime, London, Wm. Kimber. GARNER, W., 1960, An Expert looks at the Courts, 3.Forens. Sci. Soc., 1, 69-78. GRANT,J., 1966, The Future of Forensic Science, Med. Sci. Law, 6, 206-209. H. M. ADV. v. MCTAVEH,1974, High Court of Justiciary, Edinburgh, 17 September to 7 October 1974. KIRK,P. L. AND KINGSTON, C. R., 1964, Evidence Evaluation and Problems in General Criminalistics, 3. For. Sci., 9, 434. MOENSSENS, A. A., MOSESR. E. AND INBAU,F. E., 1973, ScientiJicEvidence in Criminal Cases, p. 13, New York, Foundation Press. NAPLEY,D., 1968, Trial at Law, Med. Sci. Law., 8,227. ORMROD: R., 1968, Scientific Evidence in Court (1968) Crim. L. R., 240-247. ORMROD, R., 1972, Evidence and Proof: Scientific and Legal, Med. Sci. Law., 12, 9-'20. 1I
PATTERSON, D., 1975, What can Science do for the Law? J. Forens. Sci .SOC., 15, 5. SAMUELS, A., 1974, Expert Forensic Evidence, Med. Sci, Law, 14, 17-25. ON TESTIMONY, 1957a, Effective Expert Testimony, J . For. Sci., 2, SEMINAR 73-93; 1957b, 177-193. SIMPSON, K., 1962, A Doctor's Guide to Court, p48, London, Butterworth. SIMPSON, K., 1969, The Art of Forensic Pathology, J . Forens. Sci. Soc., 9, 199. SIVE,D., 1974, Scientists in the Courtroom, In Scientists in the Legal System, Thomas, W. A., An Arbor Scientific Publishers. WALLS,H. J., 1966, Whither Forensic Science, Med. Sci. Law, 6, 183-189. WALLS,H. J., 1972, Expert Witness, London, John Long. J. A. F., 1975, Nothing but the Truth: Expert Evidence in Principle and WATSON, Practice, Estates Gazette, London.